We are at the same time (simul) saint (Justus) and sinner (Peccator). This is what life looks like for those who are in Christ. We have been forgiven and saved by grace through faith because of Jesus' death and resurrection, and this makes us saints. Yet, we also still have a sinful nature and still continue to sin while we are on this earth. But who we are is not based on our sin and what we've done. Who we are is based on what God has done for us.