Those on the side against God are sinners and those on the side for God are also sinners.
This means the spiritual war must not be conceptualized as an army of sinless human saints engaging an army of human sinners, but rather as two armies of sinners clashing together.
But this doesn't mean the sinners on the one side are the same as the sinners on the other side. The key differences between these two armies of sinners are motivation, discernment, belief, and repentance.
Those on the side against God are motivated to oppose the primacy of the spiritual, particularly spiritual freedom. If they are able to discern Good from evil at all, they inevitably choose evil. The vast majority do not believe in God and Creation, but the few that do reject both. Most significantly, those on the side against God refuse to acknowledge let alone repent sin.
Those on the side for God are motivated to live and create via the primacy of the spiritual and to increase spiritual freedom. They are able to discern Good from evil most of the time, and actively strive to choose the Good. All of those who are for God believe in Creation and work toward adding something unique to Creation. Most meaningfully, those on the side for God acknowledge and repent sin. This includes errors in discernment that may have led to bad choices.
So being against God or for God is not a matter of being a sinner or saint; it is a matter of the heart - of where the heart is oriented - of what the heart believes and thinks.
Thus, people whose hearts are oriented toward God and Creation, who have freely and lovingly chosen to align themselves with both, can remain on God's side even when they succumb to sin, provided they acknowledge the sin and repent it.
In this sense, the heart remains greater than the sin, and the individual remains aligned with God and Creation.
The clip below is taken from the latest episode of The Chosen. I believe the short scene does an excellent job illustrating some of what I have explored above. Pay particular attention to what Jesus says about the heart as Mary Magdalene repents her waywardness and sin.