[Peter] testified to [the Jews in Acts 2] that Jesus Christ was the Son of God, the Judge of the living and dead, into whom he did also command them to be baptized for the remission of sins.
Irenaeus of LyonsOthers of them employ outward marks ... They style themselves Gnostics. They also possess images, some of them painted and others formed from different kinds of material. They maintain that a likeness of Christ was made by Pilate at that time when Jesus lived among them. They crown these images, and set them up along with the images of the philosophers of the world, such as Pythagoras, Plato, and Aristotle, and the rest. They have also other modes of honoring these images just like the Gentiles.
Irenaeus of LyonsThe initial step for us all to come to knowledge of God is contemplation of nature.
Irenaeus of Lyons[Naaman] dipped himself," it says, "seven times in Jordan." It was not for nothing that Naaman of old, when suffering from leprosy, was purified upon his being baptized, but as an indication to us. For as we are lepers in sin, we are made clean by means of the sacred water and the invocation of the Lord from our old transgressions, being spiritually regenerated as new-born babes, even as the Lord has declared: "Except a man be born again through water and the Spirit, he shall not enter into the kingdom of heaven.
Irenaeus of LyonsHe who retains unchangeable in his heart the rule of the truth which he received by means of baptism will doubtless recognise the names, the expressions, and the parables taken from the Scriptures [by the gnostics], but will by no means acknowledge the blasphemous use which these men make of them.
Irenaeus of Lyons