What is the difference between a muslim and a liberal??
Quite a bit, actually. In fact, you're comparing two completely different concepts. One is a religion, the other, a political viewpoint.
I am just curious to know other viewpoints on this.
I won't go so far as to say you're lying. Even when I was a fundie, I was willing to listen to people who disagreed with me. I will say, however, that I find it really unlikely.
It seems to me that they all seem to have the spirit of antichrist.
You know what, I'll give you this one. The Muslim does disagree with your religion because s/he doesn't believe Jesus was the Messiah, merely a prophet. The liberal disagrees with your beliefs (that is, the belief of a conservative fundie) because they understand that reality has a well known liberal bias. In that sense, yes, they both oppose your beliefs, albeit for totally different reasons.
is it wrong for me to put them in the same category
Looking at it from the point of view that "they have the spirit of the antichrist," (that is to say, they disagree with your particular religious beliefs), then no, it's not wrong to put them in the same, broad category.
Looking at it from the point of view that one is a religious view, and the other a political view, then yes, it is wrong.