God did FOR US what we could never have done for ourselves. He became sin FOR US, so that we did not have to pay the awful penalty for sin. Jesus lived a righteous life FOR US. Jesus died a sinner's death FOR US. Jesus conquered sin and death by His resurrection FOR US!
No wonder Paul makes an appeal to all of us. He says, "we make it our aim to be pleasing to Him." No one will ever do more for us than Christ has already done. He did what we could NOT do. What we CAN do is live in a manner that is pleasing to Him.
So what pleases God? In this chapter Paul is appealing to believers to share with others this "good news". He says the reality of knowing Christ should compel us to "persuade people" to believe in Jesus. Who are we currently sharing with?