He 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 LyonsWhen we stand in the light it is not we who illumine the light and cause it to shine but we are illuminated and made shining by the light... God grants his blessings on those who serve him because they are serving him and on those who follow him because they are following him, but he receives no blessing from them because he is perfect and without need
Irenaeus of LyonsA man that is an heretic, after the first and second admonition, reject; knowing that he that is such is subverted, and sinneth, being condemned of himself.
Irenaeus of LyonsBut following the only true and stedfast Teacher, the Word of God, our Lord Jesus Christ, who did, through His transcendent love, become what we are, that He might bring us to be even what He is Himself.
Irenaeus of LyonsSince it is impossible, without God, to come to knowledge of God, he teaches men through his Word to know God.
Irenaeus of LyonsSuppose there arise a dispute relative to some important question among us, should we not have recourse to the most ancient Churches with which the apostles held constant intercourse, and learn from them what is certain and clear in regard to the present question? For how should it be if the apostles themselves had not left us writings? Would it not be necessary, in that case, to follow the course of the tradition which they handed down to those to whom they did commit the Churches?
Irenaeus of Lyons