The same I deal with it in every game, I act as the person I desire my character to be, in most cases calm, logical, and seasoned with a sense of justice and retribution. I do not care if it is right, but only that it is fair. I never trust demons, period. The templars are not wrong, but are built wrong. Mages should not be treated like livestock, they should be tested and trained to ensure the likelihood of possession is slimmer, they should have phylacteries maintained in case they go rogue, and there should be a policing faction capable of enforcing laws upon them just as there are for the mundanes, but they should not be Hitler'd.
Frankly I like it when others disagree with me because conflict is what drives good stories. I expect them to disagree, yet perhaps respect my choices, or try to convince me I am wrong, accept I proved them wrong, or agree to disagree. Sometimes things don't work out, but that's life too, and I respect those with enough balls to stand by their ideals and move on to meet them. I end up wishing them the best even if it means we will, eventually, become enemies.
So I'm not going to care too much, but I'm also not worried. Most likely you will have to be extreme in either direction to lose someone (CRAY CRAY) over an issue, which is unfortunate (and boring). I ended up keeping everyone happy in ME and the other DA games without much difficulty, as far as I recall.