There are many reasons why God would not want you -but don't worry. You're in good company.

Moses stuttered.
David's armor didn't fit.
John Mark was rejected by Paul.
Hosea's wife was a prostitute.
Amos' only traning was in the school of fig-tree pruning.
Jacob was a liar.
David had an affair.
Soloman was too rich.
Abraham was too old.
David was too young.
Timothy had ulcers.
Peter was afraid of death.
Lazarus was dead.
John was self-righteous.
Jesus was too poor.
Naomi was a widow.
Paul was a murderer. So was Moses and David.
Jonah ran from God.
Miriam was a gossip.
Gideon and Thomas both doubted.
Jeremiah was depressed and suicidal.
Elijah was burned out.
John the Baptist was a loudmouth.
Martha was a worrywart.
Mary was lazy.
Samson had long hair.
Noah got drunk.

Did I mention that Mosus(mosus???) had a short fuse? So did Peter, Paul-- well, lots of folks did.

But God doesn't require a job interview. He doesn't hire and fire like most bosses, because He's more our dad than our boss. He doesn't look at financial gain or loss. He's not prejudiced nor partial, not judging, grudging, sassy, nor brassy, not deaf to our cry, not blind to our need. As much as we try, God's gifts are free.

We could do wonderful things for wonderful people and still not be... wonderful.
Satan says, "You're not worthy."
Jesus says, "So what? I AM."

Satan looks back and sees our mistakes. God looks back and sees the Cross. He doesn't calculate what you did in the past. It's not even on the record.
Sure. There are lots of reasons why God shouldn't want us. But if we are in love with Him, if we hunger for Him more than our next breath, He'll use us in spite of who we are, where we've been or what we look like.