I heard a quote from a preacher sometime ago that Moses and Abraham are not in the Church of Christ (Ephesians 4:4; I Corinthians 12:13), even though they are currently saved. I understand they were never baptized into Christ; but if they are not in the body, where are they? It is my understanding that all dead saved people are currently in one place right now (Luke 16:19-31; 23:43).
The problem is the definition of terms and without being able to talk to the preacher, I cannot say he was wrong or right. The word "church," which translates the Greek word ekklesia, which means assembly, can mean a single local church (e.g. I Corinthians 1:2) or all saved under the law of Christ (Matthew 16:18). When Jesus said, "And I also say to you that you are Peter, and on this rock I will build My church, and the gates of Hades shall not prevail against it" (Matthew 16:18), it implies that the church did not exist prior to Jesus establishment of it. "Now, therefore, you are no longer strangers and foreigners, but fellow citizens with the saints and members of the household of God, having been built on the foundation of the apostles and prophets, Jesus Christ Himself being the chief cornerstone, in whom the whole building, being joined together, grows into a holy temple in the Lord, in whom you also are being built together for a dwelling place of God in the Spirit" (Ephesians 2:19-22). Being built on Jesus, it could not exist before Jesus came into this world.
But the church of the New Testament is not the only assembly of God's people. Israel was the assembly of God's people under the law of Moses. "I will declare Your name to My brethren; In the midst of the assembly I will praise You" (Psalms 22:22). In heaven all the assemblies of God's people from all ages will be combined into one great multitude (Revelation 7:9). "And for this reason He is the Mediator of the new covenant, by means of death, for the redemption of the transgressions under the first covenant, that those who are called may receive the promise of the eternal inheritance" (Hebrews 9:15).