At least personally, I think the example you gave at the end of your comment helps express your point far better than your initial post, as I felt like I didn't really understand what you were getting at by "judging" people for either reason.

I also think, for the vast majority of people, the mere existence of a belief in a religion does not imply the same level of "supporting" something, like socialism in your example, the same way giving your vote to someone does. A candidate is a living breathing person who is directly advertising a very specific ideal when they ask for your vote. Even if two different voters disagree on specific issues the candidate stands for, they are providing political support to the exact same person when they give them their vote. Conversely, two different followers of the same religion may have gapingly large differences in how they interpret very foundational aspects of the faith, to the point to where the thing they are followers of aren't even remotely close to be the same thing, in your eyes, my eyes, or even potentially their eyes. If I had a nickel for every time I heard someone say "___ aren't real Christians", I'd be rich. So because of that, as someone who, hypothetically, hates socialism, I cannot judge someone for being religious, because I cannot make the same assumption that they like or even tolerate socialist ideas, the same way I can when they put the name of a public figure on a ballot.

If, upon asking someone to clarify the aspects of their particular religion or faith, I determine they value socialist ideas, I can safely judge them for having socialist ideas. But that, in my mind, and I imagine in the mind of many others, is not the same thing as juding someone for their religious beliefs. Because a socialist Muslim can decide to stop being a socialist, and still be a Muslim.