I was just chatting with a good friend, with whom I have had many theological discussions. But it all boils down to the advice he gave me (I'm sure he wouldn't mind me sharing his words!):
His mercies are NEW EVERY MORNING – they need to be because we sin. No condemnation for those in Christ Jesus. Remember your ABCs of Evangelicalism – we sin, God forgives, we give glory.
I have always liked the theology of Karl Barth – a central tenet of which is that we alienate ourselves from God, and cannot get back to him. So he comes to us with grace and mercy – to which we respond gratefully – and God graciously accepts our imperfect worship. Our part in our salvation – simple gratitude and worship – is sandwiched within God's movement to us.
Never think you deserve it, never forget who gives it, never cease to worship such an amazing God, Jesus Christ.