When I was a Christian , I was constantly told that there was nothing I could do to remove the stain of sin from my soul. That God is so offended by sin that we are like filthy rags to Him when He considers our sinfulness. That’s why it was necessary that He die for our sins, so that our sins would be forgiven forever. Because only God Himself (in the form of Jesus Christ) could offer up a sacrifice great enough to cover all our sins.
This is the concept of “redemption:” God redeems our souls and saves us from sin by His death on the cross.
Muslims, on the other hand, believe that, as humans, we redeem ourselves, through the daily sacrifice of our selves in submission to God. We know that we will never be perfect—and God makes it very clear in the Qur’an that He knows it, too!—but it is the effort that pleases God and causes Him to be on our side.
God does not need to offer up His son as a sacrifice for our sins, because He can be merciful to us and grant us forgiveness without going through all that. After all, He is God.
Christians believe that they are transformed into people that God can bear to behold by the power of Jesus Christ and the inner work of the Holy Spirit. Jesus provides the means by which their nature can be “washed clean.” And the Holy Spirit takes over their hearts and minds (as much as they are willing to allow Him to) in order to make them into new persons.
For Muslims, God’s spirit strengthens us to do what is right, but is not a separate entity. His spirit is a part of God in much the same way that our spirits are a part of us. We don’t talk about our spirits in the third person and neither does God. His spirit is something He possesses, not another personality.
This, of course, is where Muslims part company with Christians. God does not need to split Himself into parts to accomplish His ends. He can empower and forgive us just because He is who He is. But it is up to us to decide our fate. We cannot point to God’s death on the cross and claim absolution. We are absolved by our intentions and our actions and by the degree that we are submitted to Him.
Some Christians think that makes for a very uncertain existence, never knowing whether or not we are “saved.” But since God has the power to “save” (grant us entrance into Heaven), He is also capable of sorting out who is His and who isn’t. For Muslims, not knowing for sure is not disheartening, it is motivation to keep trying to be the best human beings we can be.