If a homosexual wants to be saved and know the truth, he will listen. Many Christians will be quick to point out the obvious that a homosexual is an abomination and that they should immediately forsake their homosexual tendency. However, many Christians committed sexual sin among many other sins, so they should remember that whenever they witness to someone.
I will also say, that if the person wants to be argumentative and get into a theologic debate as to the existence of God, then it might be best to end the discussion. Many liberals or non-believers do this one.
How many parents are thrilled when their child reveals that they are “gay”? I can imagine it is less than thrilling....
That’s where my apologetics classes come in ;)