There’s a God. Only one God, in fact, and he is the creator of everything. We're made in His image, which means we're like him in many ways, except that he's God and we're not. He's loving and just and desires a relationship with us. As individuals with free will, we have the freedom to respond to the relationship God's initiated with us, or not.
We're free to choose to live outside the realm of the life God has for us as it's explained in the Bible. Put another way, many choices we make either move us closer to God or further away from him. Making even seemingly small decisions that separate us from God is called sin. We all do it, and we'll continue to do so. And, even then, God will love us and passionately pursue us.
God loves us so much, in fact, that he sent his only son, Jesus, to die so the rest of us could live. The cost of sin was separation from God---spiritual death---until Jesus came and his death paid everyone's debt. That's serious love. Because of that serious, perfect love, this gift from God is waiting for anyone who wants to receive it. This is called Grace. God gives grace freely and abundantly.
As for us, we need only to decide whether or not to believe and receive this stuff. If we decide to believe it, we have available to us a new, full life that can start now and never stop. And it's OK to have a lot of questions along the way. Although God reveals things to us (including what he's revealed about himself in the Bible), he remains mysterious and wonderful.