I was beat to it Adino. Faith and Conviction activates a small time after combat starts (within a second). If you have the game set to pause automatically when combat starts, it will still not show Faith and Conviction bonuses. So the ability itself is working.
What should change, however, is that F+C (along with other passives) should be applied out of combat as well, simply so as not to confuse new players. I was confused by this too at first, and also thought it was a bug.
Edit: It is also known and intended that F+C doesn't apply to anyone but your main, since your main does all the talking, and it wouldn't make RP sense for other characters in your party to abide perfectly by the exact same dispositions that your main does. The priest's Holy Radiance also gets bonuses like this. So if you're going to have a paladin or priest in your party, there is a strong gameplay advantage to making one of them your main.
