Interesting topic... there's several thing's I'd like to say to the original poster.
A.) Just because you thank two people in the same sentence does not mean you are saying they are the ''same.'' I don't know why you think that is, because it makes no sense. If an athlete thanked his team and his parents for always motivating him to succeed, he is not saying ''team = parents."
Perhaps he did not word it well but from what I can tell, he is only being zealous for his creator. So when Lady GaGa thanked God and homosexuals in the same sentence, he felt that God was being insulted. There's nothing wrong with that either.
B.) Maybe Lady Ga Ga wasn't talking about your God.
True but this is a moot point as the general first impression would be that she is referring to the Jewish/Christian God. If Jessica Simpson thanked God for her career, most people would assume (perhaps incorrectly?) that she means the Christian God and not say, Allah. I am not saying that we should assume or that she is necessarily referring to the Christian God. But it is reality - that is the first impression people will get whether they are correct or incorrect in the assumption.
C.) Lighten up. This ultra-conservative, making a moral issue out of everything attitude isn't going to win any converts to Christianity. Lady Ga Ga lives in a free country, she can thank whoever she wants. If you want to censor everyone who doesn't agree with you you're welcome to go find some island, start your own society with your own rules, and forget about the rest of the world.
Yes, she has every right to do so and by the same standards, so does the original poster. If he wants to be ultra-conservative, that's his choice too, right?
Also, technically, we don't convert. It's not our job though we may forget from time to time. Our job is to present the Gospel. God will speak to the hearer. If you really want to get even more technical, converts are pre-destined from God's point of view. So, there is no "winning converts" from God's point of view. He already knows who will choose Jesus and who won't.
D.) I didn't pick this avatar to poke fun, I had it before I even read this topic.
I don't think anyone would've had a problem with it even if you didn't mention it. After all, quite a few of the posters in this thread don't even know who she is to begin with much less how she looks like.

Though I have to say that her poker face... well, it isn't really a poker face... too much emotion in that photo... hmmmm...