This question only comes up when the church is viewed from a denominational standpoint, otherwise the question is invalid. Because, to look at the church in the bible, we can quickly see that the only ones going to heaven are those whom God Himself adds to the church. Consider Acts 2:47, where it is written: “And the Lord added to the church daily those who were being saved.” Becoming a member of any local church does not mean you are saved. And for the sake of the original question, I imagine that there will be some, if not many, in the church of Christ that will go to hell. Why is that? Because, although we may be considered a “member” of the church to everyone else, but if God hasn’t added us to His church, then we are not saved. The next question would be: how can we be added by God to His church? Let’s look again at the text of Act 2:47, “the Lord added to the church daily those who were being saved.” So it is only those who were being saved that God added to the church. But how were they being saved? Let’s look back to an earlier part of the text: Act 2:36-38 “’Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.’ Now when they heard this, they were cut to the heart, and said to Peter and the rest of the apostles, ‘Men and brethren, what shall we do?’ Then Peter said to them, ‘Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit.’” So then, it becomes clear that God saves those who heed His commandments, to walk away from a sinful life and bury our sins in the waters of baptism where we will receive remission of our sins in the working of God. These are the only who are added to the church, and everyone that God adds to the church are going to heaven. But we are not completely secured yet! We must continue in a life of holiness in order to remain a member of His church and be saved in the end: Colossians 1:21-23 “And you, who once were alienated and enemies in your mind by wicked works, yet now He has reconciled in the body of His flesh through death, to present you holy, and blameless, and above reproach in His sight— if indeed you continue in the faith, grounded and steadfast, and are not moved away from the hope of the gospel which you heard, which was preached to every creature under heaven, of which I, Paul, became a minister.”
Isn’t the church of Christ the group that believes they’re the only ones going to heaven?