Self Alone interpretation always leads to a direct or indirect denial of the Deity of Jesus Christ sooner or later.
People who start by only accepting the "Pharisee Approved Luther Subset of Scripture" are destined to develop doctrines that contradict one another. Contradictions like waking up one morning and deciding that what they had preached as Scripture Alone based Truth for four centuries didn't matter and began to teach the exact opposite with regard to murdering your children in the womb.
Everyone not Catholic just woke up one day and decided Superslick Christian Liberty Grease was a far better basis for what they teach than Scripture Alone and ever since they've reversed themselves on one thing after another. Whatever is popular in the society they're in the Protestant and Protestant derived groups will approve of before too long. Whether it's contraception or queers marrying one another, they'll find a way to apply a bit of Superslick CLG and give the wallets in the pews what they want.
People who accept the doctrines that lead to teaching one thing as truth based on the Bible one day, and the exact opposite the next, are denying Scripture and by doing so denying Christ Himself. They've been deceived into accepting the worship of their own, Most High and Holy Self, the same deception Eve fell for, rather than worshiping Christ and following in His footsteps.
>> “If Mary had other children then Jesus Christ didn’t die sinless.” <<
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Never before in the history of the internet has such a false and stupid comment been posted!
Just the implication that Mary could ever have been sinless is the vilest of blasphemy, since it makes Yeshua, and his apostles and the scriptures they wrote liars, but to deny her children is vile hateful evil.