All who trust in Jesus Christ are saved! Nothing else is required. Only faith in Christ! (John 3:16) (Rom. 3:28). But to have the unshakable assurance that God will keep you in the faith, all Christians need to try to do God's will, repenting and confessing when they fail. That won't keep you in the faith, but again--it will give you the absolute assurance that God will keep you in the faith (2 Peter 1:5-11).