My wife used to say that we're all going to be surprised when we get to heaven because we'll see people there that we never expected to see! God's grace is far greater than our limited vision.
No, there won't be any denominations in heaven; all the things that divide us now will vanish, and we will be united together in Christ's presence forever. Some day, Christ's prayer for His followers will be fulfilled: "Holy Father, protect them by the power of your name... so that they may be one" (John 17:11). Some day, all who truly believe in Christ will answer the angel's summons: "Come, gather together for the great supper of God" (Revelation 19:17).
Only one thing will matter in eternity - and that is our relationship to Jesus Christ. Our good works won't save us; no matter how good we are, we still fall short of God's standard of perfection. Nor will our church membership save us, if we have failed to trust Christ for our salvation. The Bible says, "Salvation is found in no one else, for there is no other name under heaven given to men by which we must be saved" (Acts 4:12).
Is your trust and faith in Christ? Make sure of your commitment to Him. Then encourage your friend to examine his own faith, to be sure his trust is only in Christ for his salvation.