And Philip said: If thou believest with all thy heart, thou mayest. And he answering, said: I believe that Jesus Christ is the Son of God.
3 Church Fathers comment on this verse
Philip's preaching acted so powerfully upon the eunuch's soul that, as they continued on their way and came to a place where there was water, the eunuch asked the evangelist to baptize him, if there were no obstacle. Philip requires only one thing from the one who wishes to receive baptism: faith from the whole heart. When the eunuch fervently confessed Jesus Christ as the Son of God, Philip baptized him.
Philip confirms that this is possible if the eunuch believes his preaching with all his heart. Philip had completed the eunuch's catechesis. Only the confession of faith on the part of the catechumen was required. The eunuch briefly expresses the essence of the Christian faith. Thus the obstacle to his baptism is removed, and Philip baptizes the Ethiopian nobleman, undoubtedly according to the commandment of the Lord Himself, Mt 28:19, in the name of the Father and of the Son and of the Holy Spirit.
The preparation of the eunuch for baptism was rather brief. By now the Apostle Philip, of course, understood why he had been commanded to come here. The eunuch, meanwhile, had long been prepared for this by teaching and by life.
Moreover, a sufficient catechesis took place here. The eunuch's answer concerning faith shows that he understood, so to speak, the very essence of the faith of Christ, saying, “I believe that Jesus Christ is the Son of God.”
It is also noteworthy that the eunuch himself made Philip understand his readiness to be baptized at the first sight of water. This means that the Mystery of Baptism had just been discussed.
And at once the zealous new recruit desired to be baptized, so that he might more quickly be counted worthy of the remission of sins and of a grace-filled life in Christ.
One must add that here, in very many ways, the assisting grace-filled help of God was manifest.
THEOSIS