One of the recurring themes that has popped up in our discussions. I’m copying the Google+ discussion so far (with Luke’s permission), hopefully we’ll just continue it here…
Saying other general passages apply, if this is a distinct and legitimate theme it’ll have distinct and legitimate evidence. These are the verses you did put forward, one of which suggests some sort of mysterious activity of God but neither has evidence of post-death belief.
“If anyone’s work is burned up, he will suffer loss, though he himself will be saved, but only as through fire.” (1 Cor 3:15) Evidence maybe for a post-salvation purgatory but no evidence of faith after death.
“in which he went and proclaimed to the spirits in prison,” (1 Peter 3:19) Evidence for something; God’s activity, but interestingly no mention of how the spirits respond.