How did St. John the Baptist rejoice over the Church, the bride of Christ?

Some disciples of St. John the Baptist came to him and said, “Rabbi, He who was with you beyond the Jordan, to whom you have testified — behold, He is baptizing, and all are coming to Him” (John 3:26). John was not disturbed, but joyfully proclaimed that what Christ is doing, is from heaven. He then seized the opportunity to confirm and clarify his testimony to Christ and to His bride — the Church. St. John answered them, “He who has the bride is the bridegroom; but the friend of the bridegroom, who stands and hears him, rejoices greatly because of the bridegroom’s voice. Therefore, this joy of mine is fulfilled” (John 3:29). St. John proclaimed his joy at the coming of the divine Bridegroom and for His bride who is united with Him. In that, he expressed what the holy men of God from the Old Testament felt towards this wedding feast.

In his commentary on Song of Songs, St. Gregory of Nyssa talks about this saying, “For the virgin’s good matchmakers — the patriarchs and prophets and lawgivers — brought the divine gifts of grace to the betrothed virgin. Custom calls these ‘wedding gifts,’ meaning by this expression presents that are given before the marriage (which are remission of transgressions, forgetfulness of misdeeds, removal of sin, transformation of nature, change of the corruptible into the incorruptible, the delight of paradise, the honor of a kingdom, joy without end). The virgin, then, when she has received these divine gifts from their good bearers, who have brought them to her through the prophetic teaching, both confesses her desire and calls upon grace to hasten, since she is already eager to savor the splendor of the One she desires.”⁹⁹⁵

St. John Chrysostom says, “It is as though John the Baptist is saying, ‘I would have been in so much pain if this did not happen, namely, if the bride was not presented to her Groom. I would have been in pain and distress, but I will not be distressed since my wish was fulfilled and the bride knew her Groom and you all witnessed that. So when I see my wish being fulfilled, I am gladdened and I rejoice.’”