Why is Why do some Christians believe it is moral to be a homosexual? a valid, highly rated question, while What drives Christians to condemn homosexuality / gay marriage? gets mod-closed?
Are questions about extremely common Christian belief not on topic? Not everything about Christianity is solidly based in the Bible, believe it or not, so a question like What does the bible say about homosexuality? is not at all equivalent, and this topic is not "Bible Only.SE" it is "Christianity.SE."
The problem with the question you note was closed was not the subject matter. No, questions about Christian belief are not off topic.
The problem was that it was a question charged with one persons personal history and really fell into the realm of Pastoral Advice Questions.
Note that that, besides yours, the other two answers that did come in dealt with a wide range of issues but concluded with counseling him on how to find appropriate help. This is a pretty good indication that the community saw this as much more than a simple Question that could have a right answer in the context of a secular site.
The title of the question was a misnomer. If that had really been all there was to the question we might have been able to make something out of it. If somebody wants to ask that question without all the baggage or help the original OP to do so, it's possible it would be constructive question. There is a real question (or several) buried in there. However, the just editing the post seemed like too big a responsibility with the possibility of further marginalizing the OP or offending others, so some of us decided not to try.
I agree with you, the questions you quoted in your answer to the Pastoral Advice Questions question are on topic, at least as far as the topic goes - but they are asked in an aggressive, making-a-point way rather than an objective, seeking-knowledge way, and I think that's much of the issue. Here are the questions you quoted:
How is it fair that I am not aloud into heaven when God was the one who made me homosexual?
In that case, should homosexuals be able to marry and love one another (husband/husband, wife/wife) but be forbidden from sexual conduct?
How can a God who created my body and mind, create a world where I am specifically hated or considered "mentally ill", and/or "not of God".
Now to me, those questions read as rhetorical, making the whole thing a rant, and thus off-topic for SE. Not because they're "pastoral advice" questions but because they're "How can you possibly believe this stuff" questions. They also make some assumptions about that aren't necessarily true and need to be questioned. But if they were reworded, I think they could be rescued - something like this:
Does God make people homosexual? If he does, how is it fair that they are not allowed into heaven?
Should/are homosexuals be allowed to marry, or have a civil partnership / a loving relationship as a couple, if they refrain from sexual conduct?
If God designed someone to be homosexual and placed them in a world where this causes them to be hated, considered to be mentally ill, or unholy, how can God be said to be fair and loving?
Frankly the only real question being asked here is "Does God design people to be homosexual?" - the rest stems from there. You could generalise it further to "Does God design people to sin?"
As you say, the point of any SE question is to help someone to solve a problem. That problem must be within the scope of the SE. If the problem here is that the OP wants to get a better understanding of what Christians believe, then great, they're in the right place. If the problem is that they understand fine, but don't like what Christians believe, then this isn't the right place to express that.
And, for the record, this is fully consistent with other SE sites. "How do I do X using Y software from Z company" is valid on StackOverflow; "How can Z, who made Y software, make it so difficult for me to do X with it" probably isn't.
