Have you ever tried to lose weight? It’s a lot harder than it seems. You fight hard to eat healthy only to slip up at dinner and order a slice of cake. How does this happen? Paul talks about it in Romans — “For what I want to do I do not do, but what I hate I do” (Romans 7:15 NIV).

As long as we inhabit mortal bodies, we experience the push and pull of our conflicting desires. We try to “just will ourselves through it.” But it’s not that simple. Our wills are only as strong as the desires driving them. When this dynamic is applied to our spiritual lives, the results can be frustrating and confusing. We might want to spend more time in prayer, to serve more, or to act more lovingly to our friends or spouses in an effort to be more like Christ, but our sinful nature influences our will — resulting in a lot of conflict.

But there’s good news. A wise man once told me that the difference between Jesus and religion, when it comes to the problem of sin, is that – religion says, “do”, but Jesus says, “done.” In his sacrificial work on the cross, the question of our sin has been answered forever. Now, this doesn’t mean the process of becoming more like Jesus won’t be difficult, or that we won’t mess up. But it does mean that we can wage this battle daily in full confidence of its outcome: Jesus wins, every time. In fact, he already has! We remain his beloved children and he has promised – “He who began a good work in you will carry it on to completion until the day of Christ Jesus” (Phil. 1:6 NIV).

As Calvin used to say, it takes perseverance and patience, repentance and renewal, mortification and vivification. But when we stand firm in God’s completed work for us, and realize that the impossible task we must “do” has already been “done,” we truly begin to walk in his resurrection power and life. What Christ has done for us, the Holy Spirit will work out in us and in his time and in his way, God will bring it to completion.

I’m Joseph Tkach, speaking of LIFE.

Originally published at GCI.org.

Joseph Tkach has been president of Grace Communion International since 1995. He holds a Doctor of Ministry degree from Azusa Pacific University.