Introduction
This chapter unveils the hidden heart of the priesthood: deep union with Christ is not a mystical luxury, but a sacred necessity. Drawing on Scripture and the teachings of St Teresa of Ávila, it reveals how the priest is called not only to celebrate the Eucharist but to live it interiorly—participating in Christ’s Passion for the salvation of souls. Evangelisation, far from being mere outward activity, flows from this invisible labour of love. A compelling call to rediscover the spiritual foundations of priestly life.
A Foundational Necessity, Not a Mystical Luxury
Union with Christ in the life of the priest –any priest– is not as a vague mystical fancy but as a profound necessity. It is the hinge on which the priest’s ordination, sacramental ministry, and spiritual identity turn. It is not an optional luxury, but rather the indispensable foundation of priestly life. The Church’s rite of ordination bears witness to this truth: at ordination, the bishop anoints the hands of the ordinand and presents the paten and chalice, saying words that reverberate with urgency: “Be aware of what you celebrate and conform your life to what you celebrate.” The priest is entrusted with celebrating the sacred mysteries, the very work of our Redemption, and yet he must never blur the distinction between the liturgy he offers and the inner life that must match it.
The Mystery of Participating in the Passion
In celebrating the Eucharist, he re‑presents sacramentally the Passion of Christ. We believe that through the Words of Consecration, the bread and wine become Christ’s Body and Blood, and thereby he joins each offering with the sacrifice of Christ on the Cross. Acting in persona Christi, the priest sacramentally offers the Eucharist and offers his whole life in union with Christ’s Sacrifice.
Yet the priest is more than liturgist. As St Paul writes, “I complete in my flesh what is lacking in Christ’s afflictions for the sake of his body, the Church” (Col. 1:24)—a mysterious phrase that theologians interpret not as deficiency in the Redemption, but as inviting the priest to a participatory suffering and co‑operation in applying the Redemption to souls. The Redemption itself is perfect and complete on Calvary, but its fruit must be applied, and priests are called to labour in union with the Redeemer so that that grace bears effect in those entrusted to them.
Spiritual Marriage: The Summit of Priestly Interior Life
Here enters the profound relevance of spiritual marriage—the highest union with Christ as celebrated by St Teresa of Ávila. In The Interior Castle, she articulates a progression of spiritual life that culminates in what she calls “union with Jesus” or “spiritual marriage”, a mystical union of soul with God. Unlike spiritual betrothal (a step before “spiritual marriage”) which may pass, in spiritual marriage “the soul always remains in its centre with its God”.
Teresa offers vivid imagery: union may be like two wax candles whose flames and wax touch closely yet remain separable; but spiritual marriage is like rain falling into a river—once the two waters merge, they cannot be separated—or a stream entering the ocean, or light entering through two windows yet becoming one (The Interior Castle, Chapter II).
Suffering and Union: A Path Shared with the Redeemer
Teresa’s theological insight unfolds clearly why such graces matter for the priesthood. She emphasises that such intimate union is preceded by purification, growth in charity, and suffering—mirroring the path of Christ and of his closest companions, especially Mary and the Apostles. She points to the example of those closest to Him, who suffered greatly, and thus suggests that profound union with Christ ordinarily implies a share in his Passion. Indeed, she explains that the transforming union brings the fullness of divine love into the soul, not transient consolations but enduring union that transforms one’s interior life and ministry.
In the context of priestly mission, this means that priests must not only do liturgy, preach, serve—but must interiorly be Christ in a mystical sense. An ordained priest is sacramentally “identified with Christ” through ordination, but that this external identity must be complemented by a mystical identity in charity: the priest becomes, with Christ, Bridegroom of the Church, serving her with undivided solicitude, “giving permission to God to do with him exactly as He wills”.
St. Teresa of Avila’s Words
“It will be a good thing, sisters, if I tell you why it is that the Lord grants so many favours in this world. Although you will have learned this from the effects they produce, if you have observed them, I will speak about it further here, so that none of you shall think that He does it simply to give these souls pleasure. That would be to make a great error. For His Majesty can do nothing greater for us than grant us a life which is an imitation of that lived by His Beloved Son. I feel certain, therefore, that these favours are given us to strengthen our weakness, as I have sometimes said here, so that we may be able to imitate Him in His great sufferings.
We always find that those who walked closest to Christ Our Lord were those who had to bear the greatest trials. Consider the trials suffered by His glorious Mother and by the glorious Apostles. How do you suppose Saint Paul could endure such terrible trials? We can see in his life the effects of genuine visions and of contemplation coming from Our Lord and not from human imagination or from the deceit of the devil. Do you imagine that he shut himself up with his visions so as to enjoy those Divine favours and pursue no other occupation? You know very well that, so far as we can learn, he took not a day’s rest, nor can he have rested by night, since it was then that he had to earn his living I am very fond of the story of how, when Saint Peter was fleeing from prison, Our Lord appeared to him and told him to go back to Rome and be crucified. We never recite the Office on his festival, in which this story is found, without my deriving a special consolation from it. How did Saint Peter feel after receiving this favour from the Lord? And what did he do? He went straight to his death; and the Lord showed him no small mercy in providing someone to kill him.
Oh, my sisters, how little one should think about resting, and how little one should care about honours, and how far one ought to be from wishing to be esteemed in the very least if the Lord makes His special abode in the soul. For if the soul is much with Him, as it is right it should be, it will very seldom think of itself; its whole thought will be concentrated upon finding ways to please Him and upon showing Him how it loves Him. This, my daughters, is the aim of prayer: this is the purpose of the Spiritual Marriage, of which are born good works and good works alone.
Such works, as I have told you, are the sign of every genuine favour and of everything else that comes from God. […]
Reflect carefully on this, for it is so important that I can hardly lay too much stress on it. Fix your eyes on the Crucified and nothing else will be of much importance to you. If His Majesty revealed His love to us by doing and suffering such amazing things, how can you expect to please Him by words alone? Do you know when people really become spiritual? It is when they become the slaves of God and are branded with His sign, which is the sign of the Cross, in token that they have given Him their freedom. Then He can sell them as slaves to the whole world, as He Himself was sold, and if He does this He will be doing them no wrong but showing them no slight favour. Unless they resolve to do this, they need not expect to make great progress. For the foundation of this whole edifice, as I have said, is humility, and, if you have not true humility, the Lord will not wish it to reach any great height: in fact, it is for your own good that it should not; if it did, it would fall to the ground. Therefore, sisters, if you wish to lay good foundations, each of you must try to be the least of all, and the slave of God, and must seek a way and means to please and serve all your companions. If you do that, it will be of more value to you than to them and your foundation will be so firmly laid that your Castle will not fall.”
Then she explains how Union helps charity:
“It is quite certain that, with the strength it has gained, the soul comes to the help of all who are in the Castle, and, indeed, succours the body itself. Often the body appears to feel nothing, but the strength derived from the vigour gained by the soul after it has drunk of the wine from this cellar, where its Spouse has brought it and which He will not allow it to leave, overflows into the weak body, just as on the earthly plane the food which is introduced into the stomach gives strength to the head and to the whole body. In this life, then, the soul has a very bad time, for, however much it accomplishes, it is strong enough inwardly to attempt much more and this causes such strife within it that nothing it can do seems to it of any importance. This must be the reason for the great penances done by many saints, especially by the glorious Magdalen, who had been brought up in such luxury all her life long; there was also that hunger for the honour of his God suffered by our father Elias;250 and the zeal of Saint Dominic and Saint Francis for bringing souls to God, so that He might be praised. I assure you that, forgetful as they were of themselves, they must have endured no little suffering. This, my sisters, I should like us to strive to attain: we should desire and engage in prayer, not for our enjoyment, but for the sake of acquiring this strength which fits us for service. Let us not try to walk along an untrodden path, or at the best we shall waste our time: it would certainly be a novel idea to think of receiving these favours from God through any other means than those used by Him and by all His saints. Let us not even consider such a thing: believe me, Martha and Mary must work together when they offer the Lord lodging, and must have Him ever with them, and they must not entertain Him badly and give Him nothing to eat. And how can Mary give Him anything, seated as she is at His feet, unless her sister helps her? His food consists in our bringing Him souls, in every possible way, so that they may be saved and may praise Him for ever.” (The Interior Castle, chapter IV)
The Invisibility of Redemptive Labour
Such mystical union is not merely personal bliss; it is spiritual labour in invisible realms. Much of the priest’s mission remains unseen: inward purification, growth in charity, interior suffering, union with Christ in his Passion—not for its own sake, but to bring the fruits of Redemption to souls. As Mother Teresa once counselled: “Spread the charity of his heart wherever you go and so satisfy his thirst for souls”.
Thus when the bishop commands the newly ordained, “Be aware of what you celebrate and conform your life to what you celebrate,” he summons the priest to an inner dynamic where the Mass is not only external rite but lived reality. Celebrating the Passion and Resurrection sacramentally is essential—but living that redeemed life interiorly is even more necessary. The priest, like the Lamb offered, must present himself as victim in union with Christ: invisible, interior, mystical—but real, vital. The fruitfulness of the priest’s ministry flows from the depth of his union with Christ.
Deep Evangelisation: Beyond Preaching and Meetings
Evangelisation is not primarily about sermons, events, or organising outreach – they are necessary of course but not enough. These visible efforts account for perhaps five percent; the greater work is the invisible evangelisation. This invisible dimension is spiritual: the priest’s union with Christ generates a magnetism of divine love, drawing souls often without words. Hidden prayers, interior suffering, presence in grace, mystical intimacy—these quietly shape conversion and sanctification.
In spiritual marriage, Teresa speaks of divine nourishment issuing outward: from the interior union, “streams of milk … bring comfort to all the people of the castle”. Applied to evangelisation, the priest united with Christ becomes a living channel: souls receive grace through his spiritual being, often without conscious awareness.
The True Formation of Future Priests
Yes, the priest’s visible ministry—celebrating Mass, preaching, pastoral care—may account for perhaps five or ten percent of the actual spiritual work, the rest is interior labour in charity, purification, mystical union, interceding in soul‑work that no one sees except perhaps his spiritual director. That interiority is not escapist mysticism, but a deep engagement in the Redeemer’s ongoing work, as part of his priestly union with Christ.
Forming future priests in spiritual life thus becomes essential—not peripheral. It is an absolute priority. They must be formed in the journey of growth in charity, purification, interior prayer, learning to love perfectly, to suffer with Christ, to unite to him so that this union births an invisible yet effective apostolate: attracting souls to God through the power of divine charity flowing from the priest’s soul.
Carrying Souls Through Mystical Union
It is precisely in spiritual marriage that this power matures. The Lord says: “Whoever believes in me, as Scripture has said, out of his heart shall flow rivers of living water.” (John 7:38, RSV) This verse is profoundly significant when applied to the life of the priest. It reveals that fruitfulness in ministry does not stem from external effort alone but from an interior union with Christ through faith and the indwelling of the Holy Spirit. The “living water” symbolises the grace and life of the Spirit flowing outward from the believer—especially true for the priest, whose union with Christ becomes the hidden source of grace for others.
Teresa writes that from the bosom of Divinity, “streams of milk” issue to nourish the servants of the castle- meaning grace flows outward to sustain others from the mystical union within. The priest rooted in Christ thus carries his sheep on his shoulders, in invisible union, bringing them mysteriously into the work of Redemption through his very being.
Theological Implications and Pastoral Reality
Ordination sacramentally configures the priest in persona Christi capitis, but spiritual marriage enables him to live this identity mystically. According to the Church’s understanding, the priest “acts in the person of Christ” especially in the Eucharist and presence to souls. Yet this sacred identity must be actualised interiorly. Growth in charity, purification, and humble surrender partner with Christ in the application of Redemption. As St. Paul says, those united to the Lord are “one spirit” with him.
Conclusion: The Mystery and Magnitude of the Priest’s Call
In summary, union with Christ for the priest is not mystical luxury but a foundational necessity. Ordination configures him sacramentally “in persona Christi”; spiritual marriage enables him to live that identity mystically in charity, interior sacrifice, and participation in Christ’s Passion. The bishop’s charge—“Be aware of what you celebrate and conform your life to it”—is a clarion call to integrate sacramental celebration and interior life. The priest must truly celebrate the Mass from inside out: offering the mystery sacramentally, and inwardly living and suffering it, thereby completing “what lacks” in the application of Redemption to souls. In that union, he fulfils his vocation as shepherd rooted in the Good Shepherd, bringing innumerable souls to God—mostly invisibly, but with enduring effect.