Patristic Wisdom: Looking to the First Sunday in Advent

For what thanks can we render to God for you, for all the joy with which we rejoice for your sake before our God, night and day praying exceedingly that we may see your face and perfect what is lacking in your faith? Now may our God and Father Himself, and our Lord Jesus Christ, direct our way to you. And may the Lord make you increase and abound in love to one another and to all, just as we do to you, so that He may establish your hearts blameless in holiness before our God and Father at the coming of our Lord Jesus Christ with all His saints. (1 Thessalonians 3:9–13)

Paul says that there is nothing so valuable that it can be enough to compensate for the salvation which the Gentiles have obtained. Since they had advanced by the perseverance of their faith and the practice of a better life, he wanted to see them all the more in order to be able to teach them what they needed to go on to perfection, the sacraments, as it were, of spiritual things which cannot easily be proclaimed, so that they might discover who and how great was the judge whom they were waiting for. It is one thing to accept the faith and another to accept its exposition. The debate about the nature of the Father and the Son is different from that about their persons. The Father is unbegotten but the Son is begotten. The persons appear to be different but the nature is one and indivisible. The unity is not in person but in substance. The Holy Spirit is not to be regarded as inferior merely because He is placed third. Whatever is clear about the second person applies to the third as well.

Paul prays that his journey will be properly organized, by God the Father first of all, because all things come from Him. He wants the power and foresight of the Father and the Son to protect his coming, so that he will be accepted by those who hear him, and the hindrances of the devil may be removed so that he can make his way to them.

In order that the joy with which he rejoices in them may be increased, Paul prays that they may grow in all good things, so that when he comes to them he may find in them even more praiseworthy things than what he had heard from Timothy. He wants them to be found blameless with the saints in the love of God the Father and at the coming of our Lord Jesus Christ, when the cross-examination starts and tests each one before His judgment seat. Paul calls Him God because of the terror of his majesty, but Father because of the kindness by which he has been pleased to adopt those who believe in Him as His children, something which will be made clear when the Lord returns.

Ambrosiaster, Commentary on 1 Thessalonians 3