I know that it is God's will for me to sing, because He has allowed me to sing many solos at my church and sing them well.
Singing at church is very different from singing professionally. Professional singing is a lot more demanding, and the record company is not as supportive and willing to overlook flubs as your church family is.
I have a friend in Christian music who told me that every year he gets hundreds of inquiries and audition CDs, and he's lucky if two of them have any real talent at all. He said most of the people who send in "fishing reels." (called that because the people are fishing for an audition and the auditions used to be recorded on tape) think they have great talent because they are on their worship team or have done solos in church.
I have another friend who couldn't accept that he didn't have the professional talent that is needed, even after he majored in worship in college, so he quit his job and moved his family to Nashville, thinking that if he was out there in the producers face more, he'd get a contract. After one year, their savings ran out and they had to move back home in shame.
My point isn't to discourage you from singing, my point is to get you to really seek God's best will for your life, to find the place he has set out for you to serve him. He has fewer people willing to scrub toilets in a homeless shelter, even though that is where the need is greatest and the workers are fewest. It's humble work, though, and few Christians are willing to humble themselves to scrub toilets for the homeless.
I'm not saying that's what you should do, I'm just saying that if you are tone deaf, God might not have built you to be up on stage singing. He might have built you to be a doctor, a lawyer, a pastor or any number of other things.
Serve Him where you are needed, not where you get the most praise.