In the gospel driven life, Michael Horton explains what “IN CHRIST” means.

Paul does not say, “Be like Jesus.” He says, “You are like Jesus.”…. It’s easy for us to rely on the gospel for forgiveness and justification but then look elsewhere for our renewal and sanctification. However, Paul says that it’s all there: “in Christ.” Only after saying this does Paul then issue the imperative to live a life that is consistent with this truth… Being in Christ is the perpetual source of our becoming like Christ, not vice versa.