Would personal testimonies not be enough?

Another important principle related to this subject that needs to be understood is that the assembly, biblically speaking, does nothing based on what only one witness says. Everything that concerns the assembly must be done according to this principle:

“By the mouth of two or three witnesses every word shall be confirmed” (2 Cor. 13:1). Also check what it says in John 8:17 and Deuteronomy 19:15. For this reason the assembly must not receive people on the basis of their own testimony. People naturally tend to give a good testimony of themselves, as the Scriptures themselves affirm: “All the ways of a man are pure in his own eyes” (Prov. 16:2). And also: “Whoever speaks of himself seeks his own glory” (John 7:18). Therefore it may be necessary to ask a person who wishes to enter into fellowship to wait. As soon as the brothers and sisters in the local assembly know the person who wishes to be in fellowship better, that person can be received on the basis of their testimony.

This is a principle that we find throughout all the Scriptures. Even the Lord Jesus Christ, the Lord of Glory, subjected Himself to this principle when He presented Himself to Israel as their Messiah. He said; “If I testify of myself, my testimony is not true [valid]” (John 5:31). He then went on to present four other testimonies that proved who He was: John the Baptist, His works, His Father and the Scriptures (John 5:32-39). Despite the various testimonies that testified of Him as being the Messiah, the Lord warned the Jews that a time would come when they, as a nation, would receive a false messiah (the Antichrist) without witnesses. He said: “If another comes in his own name, him you will accept” (John 5:43). Thus the Lord disapproved of the practice of receiving someone on the basis of their own testimony.

Acts 9:26-29 gives us an example of the care that the church at the beginning had when receiving someone into fellowship. When Saul of Tarsus was saved he wanted to enter into fellowship with the saints in Jerusalem, but he was rejected. Despite everything he had told the brothers and sisters in Jerusalem about his personal life being true, he was not received on the basis of his own testimony. It was only when Barnabas took Saul with him and presented him to the brothers and sisters, testifying of his faith and character, so that then there was already the testimony of two people, that the brothers and sisters received him. From that moment on Saul “was with them in Jerusalem, coming in and going out” (Acts 9:28).