Some ask why God things the way he did in history. To give mankind true choice, for one. And to deal with the human ability / capacity to believe untruth AS truth DESPITE all the evidence in fact against what they hold to be true. I suppose the biggest and IMHO the stupidest one is "there is no absolute truth." <--- which is a statement of absolute truth to those who believe it. If it were true then how could they say it is true because it cancels itself out.
Even in the Body Christian we have division and splits and denominations and whatnot and I don't know what all because we choose to make our own beliefs more authoritative than the Bible.
Mark 7:7-13 essentially says these traditions of man nullify the Word of God.
Now there are some blatant errors in beliefs out there, Mormons, JW's, Jews who reject Jesus as the Messiah, etc. etc. But there are in the household of God Christians who teach many many things contrary to the Bible and they will blast you from their doctrinal canons if you dare challenge them especially with scripture.
This is all why God gave the Law first and went through a religious system (Judaism) first, to get this gobbledygook out of the way and get to the heart of faith in Christ.
God's essential message to man is there are only two ways:
not God's way
That's it. If you choose to follow the traditions of men (no matter how long held by a church or denomination whatever) you are in the not God's way side of the ledger and at the top of it is the name Satan.
This is how and why Jesus called Peter Satan in Matthew 16:23 in stark contrast to Matthew 16:17. Note the difference (verse 17 God's way verse 23 not God's way).
This is true about all human philosophies...
James 4:4 (NASB95)
4 You adulteresses, do you not know that friendship with the world is hostility toward God? Therefore whoever wishes to be a friend of the world makes himself an enemy of God.
'Satan' means opposer / enemy. It's hard for us to face the truth sometimes that any of our deviations from God and God's way is actually satanic... even among believers (and / or alleged believers) in Christ.