Please see this excellent article by Yasir Qadhi over at Muslim Matters:
Dealing With Homosexual Urges: Yasir Qadhi to Muslim Student

I excerpt this core part for you:

In our religion,  the discussion of whether these urges are because of ‘Nature’ or ‘nurture’ is really quite irrelevant. And by this I do not mean that we don’t have an answer to this question. As Muslims, we believe that the fitrah that Allah created us upon is that, in terms of sexuality at least, opposites attract. But it is possible that some people have corrupted this fitrah themselves, or it has been corrupted by external methods. And it cannot even be ruled out that for some, the change in this fitrah is beyond their control.

But the point  is – and that is why I say the question is irrelevant to the Shar’i ruling -  even if somebody has such urges, it does not justify them acting upon it. Rather, what we can say to those who feel attracted to the same gender is that having such urges and conquering them is a part of the test Allah has given them. Each one of us is tried in different ways, and merely wanting to do an act is not justification enough to carry it out. [...]

I say that I’m attracted to women. Does that legitimize going after every woman I’m attracted to? Of course not. We all have our desires and urges and we must all battle them. So if you experience urges that are unnatural, you must battle them, and without doubt Allah will reward you for that.

Another point to realize is that the urge, in and of itself, is not sinful. It is simply a desire, and desires are beyond our control, hence we are not accountable for them. But to allow such feelings to persist without trying to control them is problematic. In any case, the urge in and of itself is not sinful, acting on the urge is what incurs sin. As long as the desire remains in the realm of feeling, you are not accountable on the Day of Judgment, but the second that this desire is manifested in a physical action, you are liable for all that follows.

Lastly, even if you have acted upon this urge – and we seek Allah’s refuge from this – know that this would constitute a sin. Yes, a major sin, and one that most people would be disgusted by, but realize that it is a sin alone and not kufr. Hence, even acting upon it and committing a major sin does not expel you from the fold of Islam. However, to stand up and justify it, or defend it, or write articles claiming that it is Islamic, without a doubt constitutes kufr, and not merely sin.

I would like to thank the Sheikh for discussing this issue openly, at a time when more of the “Queer Muslim” groups are springing up and promoting their unjustifiable views.