If you answer 'Lucifer' that only answers 'through whom' sin came. Besides pride is only one of sin's manifestation.
If it originated in Lucifer's heart then it is a matter of free will and what guarantee will there be that free will won't commit it anew in heaven in the future?
God is not it's author.
any ideas?
diggs, where are you?
1) Scripture shows that the angels were subjected to a trial of obedience, which some of them failed, and for which they were condemned and cast out of heaven to earth.
No remedy was provided for those who failed.
I suspect Satan's rebellion was occasioned by God informing the heavenly hosts that he intended to create matter and humans, and would give the humans to
share in the glory of the Son, in which glory the angels did not share.
I suspect the nature of Satan's greatness resulted in him rejecting God's plan to make humans greater than he, because he did not want to give up being the greatest in God's creation.
I suspect Satan then purposed to keep as many from that goal as he could, which is why he showed up in the garden, and why he goes about as a roaring lion seeking whom he may devour on earth.
I suspect that the angels who passed the trial of obedience were made immutable in their obedience, as God is immutable,
but no one suggests he dosn't have free will, even though he cannot sin.
2) Then there was man.
They were put on a trial of obedience in the garden, where Adam chose Eve over obedience to God, resulting in loss of eternal life.
Why would Adam make that choice?
I suggest it is because God created him with human emotion and desire which could conflict with obedience to God,, just as Satan's greatness could conflict with obedience to God, but Adam had the moral power to choose God over Eve, which he did not do, just as Satan had the moral power to choose God over holding on to his pre-eminent greatness.
But this time God provided a remedy for mankind, in Jesus.
3) Then there was Jesus.
He likewise was on a trial of obedience, from his temptation in the wilderness, to his agony in the garden, to his cry on the cross.
However, Jesus did not fail his trial as Adam did and, therefore, was fit to be God's remedy which satisfied his justice on the sin of the fallen men who believe in Jesus.
And I suspect redeemed mankind will be made immutable in glory, as God is immutable and unable to sin.
So where did sin come from?
From idolatry. . .in choosing the creature (self) over the Creator, the first sin in creation.