- God displays his character through Jesus
God is just. We sin and therefore we deserve hell. That's the spot we're in without Jesus. Yet God is not simply just, holy and perfect, but also merciful, gracious, loving and compassionate.
Therefore he sent his only son into the world. Jesus, who is God, became a man. He willingly came and he died for us (Christians), taking our sin and God's wrath and just penalty for that. In Jesus God displays his justice - sin is dealt with. In Jesus God also shows his love and mercy - providing a way for us to be saved "while we were still powerless" (Romans 5:6-8) and at great personal cost.
We couldn't save ourselves, but God made a way for us to be saved. Therefore he has shown for his character and his glory, bringing us to eternal salvation in him if we put our faith in him.
- Salvation isn't just for the Elite.
If we could have managed to be perfect and save ourselves. then that would mean that only the best people could be saved (that certainly wouldn't be me and probably wouldn't be you). Only the people who were completely self-controlled, completely humble, completely gentle, completely pure could be saved. Even as Christians, free from slavery to sin, we still stuff up. If we had been freed all along, we would still have sinned.
That would be bad for us - we would deserve and would get eternal destruction in hell. Jesus didn't come to save those who were well, he came to save the sick (Matthew 9:11-13) - he didn't come to save the 'good' people (since no one is good. and those who think they are are self-righteous and proud), he came to save the 'sinners' - us. Those who cannot help themselves. That's good news. In fact, thats what the gospel is all about - God saving us for his glory even though we do not deserve it one bit.
We don't deserve the salvation that we have. We couldn't achieve it ourselves and nothing we could ever have done could have made us right in God's sight.
We don't deserve it, and that's why we can count on it.
It was given freely to those who didn't deserve it, and therefore nothing that we do can make it be taken off us. If we truly love God we will serve and obey him, but we don't have to fear losing our salvation because it is entirely by grace.
Therefore, since we are saved by grace, we are free to obey God out of love, not duty. If we had to obey to get to heaven, and we lived in constant fear of stuffing it up then we wouldn't obey out of love. This way we can obey God out of love.
We couldn't do it, and that's a good thing because of Grace.