Does God punish us for our sins if we don't ask for forgiveness?
The first thing that must be established it what punishment for our sins really is - a lot of people thing the punishment for our sins comes directly from God, because God is the one we have offended by disobeying him. But this is NOT ACCURATE. It reduces God to an human parent, and a very insecure and ego-centric one at that. For more on this, go to Why Do We Have to Follow So Many Rules?
The reality is God doesn't want us to sin them because of the CONSEQUENCES that he wants us to avoid. This is the case for EVERY sin, no matter how big or how small.
By CONSEQUENCES, I mean what CAN, and often WILL happen because we sin. An example: stealing a cookie from the cookie jar - is it a sin? Well, yea, because mom, who slaved to make them, has to slave again to make more - it shows a lack of appreciation and respect for mom. It also takes away cookies from brother and sister, who have less now because of you. It also makes mom less likely to make any more for anyone, because she's so ticked off. And so on.
Stealing a cookie from the cookie jar is NOT a sin just because mom said we weren't allowed to have one, period. It's not about damaging mom's ego, or her control of the house or anything like that - at least it isn't supposed to be. When it is, usually there's something wrong with mom's attitude.
Not that it isn't a good idea not to do it JUST because mom said so, without always needing to know the reason why - that's called obedience, which can be a good thing - but that takes trust, and mom has to earn that, not expect it for no other reason than that she's mom - mom doesn't set up rules just to test our obedience either, to make sure we know that she's in charge.
And it really is that simple. It always comes down to consequences. Smoking causes cancer. Speeding causes car accidents. Gossping about the neighbors makes enemies out of our brothers and sisters. Not taking Sunday off cause nervous breakdowns and burn-out.
A sin is an act of turning our back on God. The consequence is that our backs are turned - which sucks.
Sins are not sins BECAUSE GOD SAID SO, PERIOD.
And this is something that we need to understand - God doesn't give us rules so that he can feel powerful - he's not an ego-driven dictator that gives us rules for no reason other than to exert his own authority. To understand him as such would be reducing God to an power-tripping human being, and a pretty insecure one at that. There is ALWAYS a reason why a sin is a sin.
Nor should we, when we sin, live in fear that God is now going to punish us. The punishment will be the consequence of the sin itself, which will be more than bad enough.
NOW WHAT ABOUT FORGIVENESS? Well, we're told that if we turn away from sin, seek forgiveness from God, then we will always welcome us back. When we turn away from our evil ways, God will forgive us.
In fact God has already forgiven us - for everything. This is an effect of Jesus death and resurrection. BUT will we benefit from that forgiveness if we choose to continue to sin, continue to risk the consequences of our sins coming to fruition? If we don't turn away from our sins, we remain with our backs turned. God is standing there waiting for us to turn toward him again, but we have to do the turning around ourselves - otherwise our backs stay turned.
Check out the parable of the Good Samaritan. The younger son asks for his dad's inheritance WHILE HE'S STILL ALIVE - basically saying, "Listen Dad, you're not dying fast enough for me. I want my inheritance now." Then he takes off and blows it all on partying. What a bonehead. Finally he comes to his senses and decides to go back and beg dad for forgiveness, but not expecting to be treated any better than a slave. Now the crazy part is what happens next: while the son is far off, the dad spots him on the horizon. Only one way that is going to happen - the dad had to be watching, in fact painfully watching EVERY DAY, on the off chance that maybe that day his son would return. And when he finally does, there's no penalty, no scolding, no "I told you so, dummy." The father runs to meet him, throws his arms around him, and has a celebration in his honor.
That dad is our God.
So, what if we don't ask for forgiveness? What if we don't change our ways? Will God still forgive us. The answer is, really, HE CAN'T - because we won't let him. Its those consequences - we still risk them playing themselves out when we choose to sin. But God is standing there watching the horizon, waiting for us to come home, but we have to do the "coming home" part - which is scary, but don't worry, coming back will be more than worth it.