License to Sin: Salvation by grace from the Epistles *

The doctrine of salvation by grace is most clearly shown in Paul's epistles, but as mentioned previously Muslims tend not to believe Paul.

The following verse may be the most concise explanation of the Gospel found in scripture:

For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
--2 Cor 5:21 (KJV)

Paul teaches that there are fundamentally two ways to obtain righteousness:
One is by following the law perfectly, and the other is by Christ's righteousness by grace through faith.

Some people may seem to be holy to some people if you look like you are following the laws of Moses, you should not try to do that as a way of earning your salvation, unless you can keep the whole law completely:

For I testify again to every man that is circumcised, that he is a debtor to do the whole law. Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace.
--Gal 5:3-4 (KJV)

Salvation cannot be earned, but only received as a gift.  If you try to earn your salvation, you will receive the wages of your actions:

Now to him that works is the reward not reckoned of grace, but of debt.
--Romans 4:4 (KJV)