Question:I would like to know do you believe in having to join to be a member of the "Church of Christ"?
This question only becomes difficult to answer in that I don't know if you understand the way the New Testament uses the concept of "church."
"Church" is used in two senses. One is a universal sense where we talk about all the saved people around the world and through the ages. In this sense, there is only one church. "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). Another term used to describe the church is the body (Ephesians 1:22-23) and Paul states that there is only one body (Ephesians 4:4).
But we read of the church in Jerusalem, the church in Antioch, and even seven churches in Asia. How can there be multiple churches when there is only one? "Greet one another with a holy kiss. The churches of Christ greet you" (Romans 16:16). The answer is that there is another sense to the word church. It also can refer to the brethren who live in an area and assemble together for worship. In this local sense, it doesn't include people who have already died, nor does it include people in other localities.
When we see Saul coming to Jerusalem, we read, "And when Saul had come to Jerusalem, he tried to join the disciples; but they were all afraid of him, and did not believe that he was a disciple. But Barnabas took him and brought him to the apostles. And he declared to them how he had seen the Lord on the road, and that He had spoken to him, and how he had preached boldly at Damascus in the name of Jesus" (Acts 9:26-27). Saul had become a part of the universal church, when he was saved (Acts 2:47), but he later tried to join a local church and was initially rebuffed. The church in Jerusalem, in this case, was in the wrong. They excluded someone they should not have, but we understand their misgivings and they did eventually straightened out the situation.
Similarly, among the seven churches in Asia in Revelation 2 and 3 we see several churches including people who should have been rejected. They are soundly scolded for this, but again, we understand people are involved and they make mistakes.
With that in mind, must someone be a member of a local church? Since this has been answered before, see "Does a person have to attend church?" for details.