We have found the Messiah
After Andrew had stayed with Jesus and had learned much from him, he did not keep this treasure to himself, but hastened to share it with his brother. Notice what Andrew said to him: We have found the Messiah, that is to say, the Christ. Notice how his words reveal what he has learned in so short a time. They show the power of the master who has convinced them of this truth. They reveal the zeal and concern of men preoccupied with this question from the very beginning. Andrew’s words reveal a soul waiting with the utmost longing for the coming of the Messiah, looking forward to his appearing from heaven, rejoicing when he does appear, and hastening to announce so great an event to others. To support one another in the things of the spirit is the true sign of good will between brothers, of loving kinship and sincere affection.
Notice, too, how, even from the beginning, Peter is docile and receptive in spirit. He hastens to Jesus without delay. He brought him to Jesus, says the evangelist. But Peter must not be condemned for his readiness to accept Andrew’s word without much weighing of it. It is probable that his brother had given him, and many others, a careful account of the event; the evangelists, in the interest of brevity, regularly summarise a lengthy narrative. Saint John does not say that Peter believed immediately, but that he brought him to Jesus. Andrew was to hand him over to Jesus, to learn everything for himself. There was also another disciple present, and he hastened with them for the same purpose.
When John the Baptist said: This is the Lamb, and he baptizes in the Spirit, he left the deeper understanding of these things to be received from Christ. All the more so would Andrew act in the same way, since he did not think himself able to give a complete explanation. He brought his brother to the very source of light, and Peter was so joyful and eager that he would not delay even for a moment.
~St John Chrysostom