No I wouldn't stop them from taking communion assuming they have been baptized. Its not complicated. Though I see baptism as part if the Christian experience I believe the point if salvation is when the sinner is justified by faith and is now at peace with God. There are tons of opinions on water baptism, as long as one affirms that a believer ought to be baptized then what's the big deal. I think we as men too often take it upon ourselves to cull the church.
Now if someone absolutely refuses baptism, then as I said before, we'd discuss it, I'd show them the scriptures, also have them consider church history, and if they still refused I'd have to tell them that I was sorry but so far as I understand the scripture all those who have repented if their sins and trusted in Christ identify with Him through water baptism (would probably emphasize
Romans 6:1-5). If we just couldn't agree that a person need to be baptized then we'd probably need to part ways.
I don't try to keep everybody. I openly tell people if you don't want to attend church here, please find another church, but go to church somewhere. If someone leaves I tell them I pray that they will find a place they can serve God and grow. Of course it hurts when someone leaves but I've found it much better to just take the high road and know if they are one if His sheep He will guide them. If not, they were temporary anyway. When I was OP if someone left many times all hell was prophesied over that person. Divorce, drugs, backsliding, etc. I don't do that. I don't want or like losing people.
But I'm a pretty conservative guy in a post modern world. Our church isn't going to be for everybody. We are not seeker sensitive. My goal is to glorify God and faithfully proclaim His Word. If someone is looking for a church that is centered on the Word of God, a personal relationship with Jesus Christ, a desire to grow in holiness, and a desire to reach the lost then there is a reasonable chance they may like our church.
If someone is looking for good music (we use tracks), a big youth program, lits if extra curricular activities and various small group ministries (mens , women's, married, singles, teen, tweens, divorcees,cowboys, bikers, etc, etc) we are probably not a good fit. Were just a small basic church.
If someone wants a church where the sermons are tailored to the congregation, surveys are handed out to see what topics they would like to hear, if they are looking for a church that raffles iPods, TVs, and Ford pick up trucks. We're not for them.
If someone wants a church where the preacher doesn't define sin by name, doesn't proclaim all other (non Christian) religions false, talk about the wrath if God, the blood of Christ, and the dangers if false conversion. They'd probably be more comfortable elsewhere.
If someone doesn't think homosexuality is a sin to be repented of and abandoned, you guessed it.
So these things being so I have to accept that the church isn't for everyone. Its not that I want to run a single person off or offend anyone. I am greatly discouraged by every single visitor that doesn't come back or those that attend a few weeks then disappear. I wonder if I am the problem. But I do keep in mind that as long as I hold to that church philosophy in thus culture its not going to be for everyone and I just have to live with that.