I'm sorry, this might be long and rambly.
As someone who is part of the LGBTQ+ community I don't think you're a homophobe. You don't have to openly advocate for things in order to be a good/nice person. Just treat someone as a human being, with a base amount of kindness, until you know more about them.
Each person should be met at face value, in my mind, based on their personality, with room for change (I'll explain in a moment). If you don't like someone BECAUSE they have a disability, then you're ableist. If you don't like someone because they're an absolutely horrible person, but they happen to be in a wheelchair, that doesn't make you ableist, you have a right to not want to be friends with that person because you've found out that they're not nice.
The same with gay people. If you're pleasant to people in the community, but you learn later on that they're absolutely the sweetest person you've ever met, and you want to become friends with them, then you're likely to treat them even better than before due to building a friendship bond. (And the opposite is also true same as the above example).
If, for example, you found yourself in this position of friendship, and your feelings on homosexuality prevented you from wanting to pursue a further/deeper friendship with this person, then you'd have to think hard about whether or not you're truly as accepting as you think you are. Acceptance, tolerance, friendships and relationships are SO much more confusing and complicated than just "you're good, you're bad".
It's about the individual person, not about a community as a whole, I think that's where people get confused. Let's have another example. Let's say your gay friend that you've made and yourself have become quite close, best friends or something. Let's say that friend really wants you to go to a gay pride with them. Would you go? Would your beliefs stop you from going? This is where it becomes complicated. Because you have to separate the two things. Would you go to support your friend, who trusts you so much that they want you to join them? Would you have the heart to say no because of your beliefs? Or would you go because you want to support THEM, over wanting to support homosexuality in general? You're not a homophobe if you're not actively advocating for LGBTQ+ rights or whatever, but if your beliefs are affecting the way you treat people in the community, even just a small bit, that's something you'd have to look at.