I think the phrase should be "Puerile Substitutionary Atonement" (I'm avoiding the obvious pun "Penile").

Speaking of heresy, may I recommend G. K. Chesterton's "Heretics." I don't know it it's ironic or simply the way of things, but Chesterton's earlier work is more illuminating than his slightly later "Orthodoxy." It's probably easier to point out the flaws in someone's argument than the truths in one's own stance. In any case, both works are worth a read.