Were you? If these non biblical issues were so critical for believers, God is smart enough to have preserved them in the Scriptures.
2 Timothy 3:16
All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
Things not found in Scripture may or may not be of God. All depends on how they stay faithful to the Inspired Word.
And that is what all cults say. Secret revelations, oral traditions passed down, other writings etc.etc. Think hard, if it was important enough, god would have preserved it in His Inspired Word.