It's not a Cult!

Creating a faith costs piety scaled by how much you change, so change almost nothing. The wiki build: a custom Catholic ruler aged 27+ with a theology education, who starts with enough lifestyle XP to take the Prophet perk (Learning lifestyle) immediately - it slashes the piety cost. Tweak a tenet or two, hit Create Faith, done within the first year. Design the virtue list thoughtfully and you've set up Paragon of Virtue too.