Morality and Religion

One of the reasons why I’m not Christian is because I disagree with its sexual ethics. Recently, I’ve been thinking about whether or not my objection to Christian sexual ethics gives me a sufficient reason to reject Christianity. I’m thinking yes, and the argument goes something like this:

1. Arriving at a moral judgment after good philosophical reasoning provides a person with a sufficiently legitimate reason to believe in that moral judgment.
2. I have arrived at the following moral judgment after good philosophical reasoning: Sodomy is morally permissible.
3. Therefore, I have a sufficiently legitimate reason to believe that sodomy is morally permissible. This follows 1 and 2.
4. It's rational for a person to reject a religion, if the religion advocates for a moral position that opposes the person’s moral judgment that she has a sufficiently legitimate reason to believe in.
5. Christianity advocates for such an opposing position.
6. Therefore, it is rational for me to reject Christianity. This follows from 4 and 5.