Board Thread:General Discussion/@comment-26826023-20160201071856/@comment-27620479-20160405080643

Asgore's first sin is called "wrath", or "anger". He has already recognized and regretted his decision and actions out of it, but has done little towards atonement.

His other sin is "sloth", because he was too weak to admit his mistake. The amount of bad consequences emerging from that is up to interpretation, but the most obvious is that Toriel left him.