I'm not a McCain fan, but this is somewhat...I don't know, narrow-minded maybe? Do you support 100% of the positions of whatever candidate you vote for? I doubt anyone does. We vote for the person most closely aligned with our beliefs. There are often many things we disagree with. Sometimes we're voting for the person the least far away from our beliefs (that's been my recent experience).
War may be your big issue. Someone else may be against the war but abortion is their big issue, and they'll vote for McCain because of that (or Obama-it swings both ways). Saying in essence that someone is a war monger if they vote for McCain is...I'm still having trouble with a good word, but it isn't right.
I agree that in general, we are forced to pick someone who (very) imperfectly represents our beliefs. However, I don't agree that this war is just one of many issues that you can agree or disagree on with respect to a political candidate. This war goes to the very foundation of our country. I think war mongering is exactly what Bush and his cronies did in the lead up to the war - did you read the link I posted earlier? They deliberately lied to drag us into this war. They not only lied outright, they also manipulated the media to lie on their behalf, hired retired generals to tout their war mongering message on CNN, etc, and used political tactics to scare people away from speaking out (see: Valerie Plame). Is this still America when our government so brazenly lies to us? Is this still America when the deaths of over 4,000 soldiers don't even have to be justified?
We now have a candidate, McCain, who has vowed to continue Bush's policies in Iraq because they are "working". He has also said many times that he would like to invade Iran. You may want to pick a prettier euphamism, but to me, that is war mongering.