Did Christ promise to be with us unconditionally? From the Priestless book the Spiritual Sword (1771)

Concerning the fact that although Christ promised to remain in a certain manner until the end of the age, nevertheless He did not remain because of transgressions.

There are some who wish to establish that the priesthood remains forever, even apart from the episcopacy, who say: ‘How then is it possible to exist without priests and to obtain salvation, since to them are entrusted all the mysteries of the Church — baptism, the Eucharist, marriage, and the others — and to them the Lord Himself promised to remain until the end of the age?’ Concerning this, it is written thus in the book On the True Faith: ‘He did not wish, when departing from earth to heaven, to leave His inheritance without order; but taking two silver coins, He gave them to the innkeepers, that is, the Old and the New Testament. And to whom did He give them? Who are the innkeepers? The Apostles, and after them their successors — pastors and teachers, archbishops and bishops — who are ministers of the majesty of His dispensation; to them He made the promise to remain until the end of the age.’ Chapter 7, folio 59.

We know, and know with complete certainty, that the Lord promised to remain with all who believe in Him until the end of the age. For He Himself said with His most pure lips: ‘And lo, I am with you always, even unto the end of the world’ (Matthew, pericope 116). But the Lord remains with us when we ourselves desire it. For He does not remain with us unconditionally whenever we, by our own iniquities and transgressions, remove ourselves from Him. A trustworthy witness to this is Saint John Chrysostom, who says thus in the Apostolic Homilies (folio 2358): ‘This also the Lord declared when He said to the disciples: “Lo, I am with you always, even unto the end of the world.” But this happens when we ourselves desire it. For He will not always be with us when we make ourselves far from Him.’ Apostolic Homilies.

Only raise the eyes of your spiritual understanding and diligently examine the Holy Scriptures, and immediately you will see that although the Lord many times promises to remain with us all days until the end of the age, nevertheless He does not remain. What then — did He lie? God forbid. For every man is false, but the Lord alone is Truth. As He Himself testifies with His most pure lips: they made themselves unworthy of His promise through transgression of the commandments of God. Therefore He turned His face away from them as from the unworthy, and altered His promise.