So where does all the sin in the world come from today? Is Satan in chains currently?
I think the problem lies with the view we have of time; how can a Christian be forgiven but still wrestle with sin & do things that are sin.
Revelations is symbolic with respect to amount of years.
1000 years is a metaphor, not a literal “1000 years”.
Sin is real; its a residual, as it were, from the Fall ( “all have sinned & fallen short”) and originated with Lucifer/Satan.
Born again Christians still have sin/can sin, but they also have the indwelling of the Holy Spirit on account of Christ’s work at Calvary.
Satan is limited/chained/short-leashed; a beaten adversary.