What are the 3 things God Cannot forgive?

In this statement, Alma outlined for Corianton the three gravest sins that are viewed with disdain by God:

1. the denial of the Holy Ghost,
2. the act of taking innocent life, and
3. the commission of sexual immorality.

Among these, adultery is considered the third most grievous offense, ranking just below murder and the sin against the Holy Ghost.