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>> “ The folks who claim extra-biblical stuff INSIST that much of it is NEEDED and VITAL to salvation and pleasing GOD” <<
All that is needed for salvation, and pleasing to Yehova was declared by Moses in Deuteronomy. That is what Paul wrote his epistle to the Hebrews to explain.
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Well; if a person clings to that, it's no WONDER they toss away John 6:28-29.