BTW:
Show me where in the New Testament Jesus tells the apostles and disciples to write a “New Testament,” and that these writings are to be the ONLY source of truth for believers.
First, let's define truth to not include the sum total of all knowledge of science, math, history, etc. That argument is so old and makes one look foolish if it is employed.
We do have the written accounts so someone told somebody to start writing. And we know that was the Holy Spirit who moved the writers to do so.
We also know from early church history there were false teachings that were beginning to creep into the church...hence the need for a written collection of agreed upon texts by the church for use in the services to determine "truth". We also have John writing in two of his contributions that accounts were written so that we may believe Jesus is the Christ and if we believe we have life in His name (John 20:31, 1 John 5:13.
If the catholic attempts to fall back on John 20:30 (aka the catholic carte blanch verse), and they usually do, then "truth" is opened up to a variety of sources.
The Mormon could make their claim that Jesus did indeed visit North America. They could also appeal to the Book of Mormon as "truth".
The Hindu could also appeal to their writings as could the Muslim.
So unless the Bible is the only source of our spiritual truth and guide to knowing Christ and how to have eternal salvation, then you open yourself up to almost anything.
Apparently the early church was comfortable and understanding they needed an agreed upon source for truth. They chose the 27 books of the NT we have today along with the 39 books of the OT as their source of truth.
If it was good for them, it should be good for us today.
And??
Show me where in the New Testament Jesus tells the apostles and disciples to write a “New Testament,” and that these writings are NOT to be the ONLY source of truth for believers.