Righteousness shall go before him,
and peace shall be a pathway for his feet.
From the Great Cloud of Witnesses:
Irenaeus was born in Smyrna in 115 and studied under the bishop Polycarp. He became the Bishop of Lyons in Gaul (today, France) and wrote extensively against the gnostic movement which posed a threat to Christianity in the second century. Gnosticism claimed to be a sect of Christianity, yet at the same time, denied that Christ had come in the flesh - thus invalidating the crucifixion and resurrection. Irenaeus' Against Heresies is a brilliant apologetic work, pointing out the flaws of gnosticism and the truths of orthodox Christianity.
For his writings: http://www.earlychristianwritings.com/irenaeus.html
Short bio: http://www.earlychurch.org.uk/irenaeus.php
Collect:
Almighty God, you upheld your servant Irenaeus with strength to maintain the truth against every blast of vain doctrine: Keep us, we pray, steadfast in your true religion, that in constancy and peace we may walk in the way that leads to eternal life; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, now and for ever. Amen.