Unfortunately, the part you’re missing regarding the authenticity of true Christianity is that it is not determined by conformity to the Bible, but by the Church.
You can cite what you consider theological discrepencies until the cows come home, but what you can not cite is a verse that tells Christians what constitutes Scripture, let alone one that makes Scripture the final authority of faith and practice.
Based upon what authority are you telling me this? (You would probably say based upon Christ's verbal authority of establishing the church)
So ya wanna tell me what difference there is between the authority of Christ establishing His Church and the authority of Christ's words in the NT? Or the authority of the Holy Spirit speaking through men in the Bible?
You're not claiming that Christ or the Holy Spirit have no authority, are you?