"'The life I live in the body, I live by faith in the Son of God, who loved me and gave himself for me.'" NIV translation
After we are crucified with Christ, He lives in us, through the Holy Spirit, and that life is by faith. That new life is trusting Him in every situation and following His guidance.
"'I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!'" NIV translation
When you try to add anything to grace then it stops being grace which is a gift.
If there would have been any other way for us to be fully restored in our relationship with God, then there would have been no reason for Jesus to go to the cross.