Here's my way of summing up the gospel: "A perfect God gives his perfect Son's life for perfectly evil creations to give them perfect righteousness.
In light of the amount of superlatives in that sentence, is there anything we should withold from God? He has given us the perfect gift--all of our life should be spent trying to live in a manner worthy of the gospel. Paul says: "be imitators of God," and "walk in a manner worthy of the calling to which you have been called." As I read the Bible, I can't help but realize my failings as a Christian, in that I do not imitate God or walk in a manner worthy of my calling. What I've realized is that to imitate God, one must live perfectly. Not perfectly like you will never sin--you will. But striving with all your heart, mind, and strength to walk in a manner worthy of the perfect gospel.