When he came. This return of Saint Timothy coincides with the one mentioned in Acts: "When Silas and Timothy came down from Macedonia" (Acts 18:5). At least no other case known in Scripture can be indicated. Accepting this makes unnecessary conjectures about some other time. However many such conjectures have been built, they are all incompatible with the circumstances of the writing of the epistle, which are mentioned in the epistle itself.
Having brought good tidings. "Do you see Paul's joy? He did not say, having reported, but having brought good tidings. So great a good did he consider their firmness in faith and love" (Chrysostom). The joy was so great that he called the news about it good tidings, using a word that in the New Testament usually means the glad tidings of the world's salvation by the Lord Jesus Christ.
This news concerns the sphere of the dispensation of salvation, like the news of the birth of John the Forerunner (Lk 1:19). The Apostle's joy over it flowed from the spirit of apostleship. This spirit zealously sought to plant everywhere saving faith in the Lord, and it was satisfied only when it saw that those who heard the preaching believed, cleaved to the Lord, and remained faithful to Him.
The assurance that the Thessalonians were such calmed and delighted the Apostle's spirit. He could not call the news about this anything other than gospel for himself.
What was the good news brought by Timothy? It concerned the truly Christian disposition of the Thessalonians, expressed in faith and love. It also concerned the preservation of good relations with the Apostle, shown by their remembrance of him and desire to see him.
Having brought good tidings of your faith and love. Faith and love, for the Apostle, are the essence of Christianity. Neither faith without love is worthy of praise, nor love without faith has value. Therefore, when he teaches, he teaches that all should hold faith working together with love, assuring them that without these everything else is nothing before the eyes of God (1 Tim 1:5-6).
When he praises someone, he praises for faith and love. So it is at the beginning of nearly all his epistles. In the words having brought me good tidings of your faith and love, the Apostle said the same as: he reported to me that you remain true Christians.
And that you have good remembrance of us. Good remembrance is remembrance with good disposition, warm and heartfelt, the fruit and witness of love for the Apostle. Or good remembrance means a kind remembrance, in the sense in which we say: he left a good memory of himself. They remember the Apostle with good feeling, considering him their true benefactor, as a true messenger of God.
"You remember me with praise and approval," Theophylact explains. Such remembrance gladdens the Apostle not as remembrance in itself, but because it signified attachment to the faith that he had handed on to them. Saint Chrysostom says here: "Herein lies the praise, that not only when we were among you and worked miracles, but even now, when we are far from you and suffer beatings and endure countless calamities, you have good remembrance of us."
Always desiring to see us. Some refer always to you have good remembrance, as in the Russian translation. Others refer it to desiring to see us, as in Slavonic. This does not change the thought at all, but the Slavonic is better. Good remembrance was stirred by the constant desire to see the Apostle, and this flows from love for him.
The memory of the heart, expressed in the desire to see the Apostle, is stronger and more unshaken than the memory of the mind. The latter was established on the former. If it was constant, this was because the desire to see him, born of love, was constant.
As we also desire to see you. If the Apostle had not added this too, the portrayal of his sympathy for the Thessalonians would have been incomplete. Mutuality is the soul of heartfelt communion. It was certainly consoling for the Thessalonians to know that the Apostle had been assured of their love for him. "For to one who loves, it is very pleasant if the beloved knows that he is loved by him" (Chrysostom).
But incomparably more consoling had to be the assurance that he was the same toward them as they were toward him. All these reminders in the Apostle were not merely customary turns of speech in written communication. They expressed the truth itself and were all directed to one goal: to inspire the Thessalonians to value the faith they had received, to love it, and to stand firmly in it.