Tim Keller wrote, "There are two ways to read the Bible. One way to read the Bible is that it’s basically about you: what you have to do in order to be right with God, in which case you’ll never have a sure and certain hope, because you’ll always know you’re not quite living up. You’ll never be sure about that future. Or you can read it as all about Jesus. Every single thing is not about what you must do in order to make yourself right with God, but what he has done to make you absolutely right with God."
When it comes to being right with God, Keller made it clear. It's all about Jesus. It's not what you have done, but what Jesus has done for you. That's the Gospel (Romans 1:16). Yes, it's all about Jesus. He died for your sins. He is risen from the dead. He is your Lord (Romans 10:9).
It's all about Jesus, not about you doing better nor trying harder. Rather, it's simply resting by faith in Jesus Christ who is your righteousness with God. The only way that you can be right with God is in Christ alone (2 Corinthians 5:21; John 14:6; Acts 4:12).
When it comes to being sure you are right with God, it's all about Jesus. Assurance is not about what you have done nor what you will do. It's all about what Jesus has done for you and what He is doing in you. Tim Keller was right. Faith is sure in Christ alone. He works in you what is pleasing to God (Hebrews 13:21).