How can man truly have remission of sin if they are continually falling from grace?
Men do not fall from grace like that, not with EVERY SIN.
They are either saved or not.
Yes a saint could sin and still be a saint.
But a saint does not lose salvation every time they sin.
The doctrine on remission of sin makes it clear that we are forgiven of all of our sins when we confess Christ Jesus as Lord. We are made right by Christ's blood for ALL of our sin. It is separated as far as east is from west. We are forgiven. We are NEW.
A saint chooses to disobey and is still saved or was never really saved at all.
What do Arminius really think about remission of sin?