Varis was born on a Fuedal World to a family of serfs. His parents died from their toil when he was young, and instead of accepting his fate, Varis ran off and joined a bandit gang. He spent most of his teenage years with them, until the lord's men found their camp and burned it, killing most of Varis's fellows. The few survivors of the battle agreed to disband and make for parts unknown, but Varis headed back to the camp, for reasons he is still unsure of. Once there, he found a lone cleric performing last rites over the dead, soldier and bandit alike.
Varis had always considered himself a heretic for forsaking his lot in life when he joined the bandits, and doubly so for serving himself instead of the Emperor's will. Seeing a cleric perform rites over his fellows made Varis wonder if there truly was redemption available for him; he rushed forward, and began questioning the cleric. The man said that an honorable death would atone for a lifetime of crimes, and though most of the bandits had not earned it, he would perform this service for them, that the Emperor might recognize his own. Varis immediately pledged his life to the Ecclesiarchy, and began training as a redemptionist.
In his training, Varis became convinced that, as his death would absolve him of his current crimes against the Imperium, it also frees him to act as he must in service of the Emperor. He believes that no action is truly heretical as long as it is performed in the Emperor's service. He knows that this is an unpopular view, to say the least, and so keeps it to himself, but he will act on it.