“ they attempt to use the Bible (that was written by early Catholics)
Scripture was written by God, as His Spirit moved men.
2/3 written before the birth of Christ.
Thou shall not steal, ADSUM.
And even most of the New Testament books were written, copied and dispersed by 50-65 A.D. The latest ones no later than 95 A.D. (those by the Apostle John). So within a few decades after Christ's ministry on earth, the written record of His teachings and the further revelation of the Holy Spirit to the Apostles writing the epistles to the churches were on their way to becoming a complete collection of Holy Spirit-inspired writings. God did not leave us to the oral tradition alone but ensured we would have a "more sure word of prophecy" with which to base our faith upon. The books that were looked at as the Old Testament, or the oracles of God given to the Jews, were already centuries old by the time the Christian faith began. They were the foundation upon which the New Testament was built as Jesus fulfilled the promises contained therein.
Just because formal declarations of "canons" recognizing the writings as a collection honored as Divine inspiration by the Christian community didn't happen for centuries after the Apostles died it didn't mean they weren't already held as such and used to establish and defend the rule of the Christian faith. As early as the start of the second century, church leaders espoused as authoritative ALL the books we currently recognize as the New Testament.
A few articles about that process can be found HERE and HERE.