Q: Can a sinner serve in the worship team?

1 Corinthians 4:2-5
"Now it is required that those who have been given a trust must prove faithful. I care very little if I am judged by you or by any human court; indeed, I do not even judge myself. My conscience is clear, but that does not make me innocent. It is the Lord who judges me. Therefore judge nothing before the appointed time; wait until the Lord comes. He will bring to light what is hidden in darkness and will expose the motives of the heart. At that time each will receive their praise from God."

Q: Can a sinner serve in the worship team?
A: Remember that a place in ministry is something entrusted to us, and not achieved by our own efforts

Q: Should we judge other sinners?
A: We often sometimes do, but as a Christian its not so much on US judging THEM. but more of, if someone else judges me then what do i do? as a Christian, we should know that what matters is God's judgement on us. So if the sinner thinks he is being judged by the church (human courts) than he really needs to take a look inside himself and the relationship between him and the Judge.
*btw, we shouldn't even judge ourselves (least we judge wrongly), we should seek God and see what He thinks of us

Q: Just because i think it is right, does it make it right?
A: even if you had passionate, genuine, all-out faith/belief in something that isn't true doesn't make it true. Even if you think you are not doing wrong, doesn't make you innocent.

Q: what is "innocent" in refference to?
A: To the law set by the One who will judge at the end of the day. Remember: He demands obedience, not sacrifice (1 Sam 15:22)

Q: what if i still really wanted to serve without any bad intentions?
A: then as a fellow loving child of God, by all means go ahead, when the Lord comes He will know the motives of your heart in all that you've said and acted out. And to each who listens to Him, they shall receive something only a God of love can do.