When Paul was mentoring Timothy, he wrote him a letter and in it he told Timothy, in 2 Timothy 3:16 saying, “All Scripture is inspired by God and profitable for teaching, for reproof, for correction, for training in righteousness; that the man of God may be adequate, equipped for every good work.” Paul was referring to the Old Testament because the New Testament was not yet written so Paul was not referring to the New Testament.
Before the Messiah (Yahoshua) was crucified, His teachings came from the scriptures (Old Testament books of the Law and Prophets). After His ascension into heaven, his disciples continued to expound the scriptures in their teachings as they reiterated the teachings of Yahoshua (see the book of Acts, Hebrews etc.). The apostles based their teachings on the scriptures (Old Testament). It was the Old Testament that was read in the synagogues and it was the source from which Yahoshua and His disciples taught righteousness.
The books of the New Testament were written decades after Yahoshua ascended to heaven. It is a record of the works and teachings of Yahoshua, acts and teachings of the apostles; conflicts in the first century churches; the spiritual condition of the churches during the first century, persecutions against the apostles’ teachings from the Pharisees and the Roman government; and the Book of Revelations. The New testament is an excellent resource of encouragement and clarification of the application of the law based on the teachings of Yahoshua, a means to measure where we are spiritually in comparison to the teachings of Christ and where we stand in comparison to the Christian movement of the first century.
Pray for discernment as you listed to preachers and evangelists and how they interpret Bible passages. Our goal as children of God is to grow in righteousness. The opposite of righteousness is unrighteousness is sin (1 John 3:4 “Whosoever commits sin transgresses [breaks] also the law: for sin is the transgression [breaking] of the law.”) I pray this answer helps to clarify this issue.
May YHWH richly bless you with the fullness of His Holy Spirit through the wisdom of our savior, Yahoshua as we strive to grow in righteousness; and I look forward to hearing from you soon.