I'm reviewing a book Atheism for Kids and for the most part it is pretty objective (just the facts, ma'am). But then there's this page which felt very slanted. As I thought more about it though, I realized this is what many "christians" actually believe – and that's a problem.
Bare with me as I give some over-simplified explanations.
The short answer is we are not good enough to be in the presence of God. Our self-centered nature would be overcome by his Glory. You would not allow an active rapist into your family and God would not allow a sinner into his.
But we are all sinners, so who goes to Heaven? People who repent and turn to God as the rightful ruler of their life (instead of themselves). Jesus took the punishment we deserve and are covered by his righteousness.
As for prayer, we do not change God but prayer changes us. We pray to align our will with God's – not the other way around. So when we pray for rain, we are recognizing God's sovereignty over His creation. We are saying [if it is your will] please send us rain for our crops [because you are in control, not us]. We pray every day because we need to remember this every day.
And finally, we are not saved by our works, but by our faith. Are you in love with your spouse because you gave them a gift, or do you give them a gift because you are in love with them? We do good works (etc) because we have faith and trust God.