Most people define sin as “Not obeying or doing God’s will.” It’s a standard definition.
Paul tells us that “whatsoever is not of faith is sin.”
Therefore, by default, even though few will admit it, faith is doing God’s will.
Many have the idea that faith is agreeing with something in your head. You heard the facts and conclude, “Yeah, ok, I can go with that.”
But faith leads to action. The root word, in the Greek, actually includes the idea of being persuaded to the point of obedience.
Hebrews 11, all about biblical characters who had faith, all DID something–mainly, they did what God told them to do.
We all inherently know this, it just makes too much sense. Faith is not proven by saying you believe, nor by raising your hand, nor by having someone dunk you in water.
Faith is proved by works, by the new life that comes that looks like Christ and not like a sinner.
However, in recent years, Christianity has gotten wimpy and backed off this point entirely. We’re afraid of works-righteousness and sounding like we’re saying people are saved by works.
As much as I sympathize with the concern, I believe we’ve gone too far in the opposite direction. To the extent that some have said you are still saved by faith even if you grow to deny Christ and become an atheist.
That is complete idiocy.
Paul speaks in Romans of the “obedience of faith.” Disobedience is sometimes used in the Bible as the antithesis of believing.
Faith is obeying God’s Word. How do you know you are saved by faith? Because the just shall live by faith.
Christ has done everything necessary to make you right with God and to remove your sin. You believe He died on the cross, was buried and rose again.
This isn’t just a head knowledge of facts about Christ; it’s an identification (according to Romans 6 and many other passages) with His crucifixion, burial and resurrection. We are raised up to newness of life. A life that is yielded no more to sin but to righteousness.
As Paul says, “Faith which worketh by love.” Faith works. It does stuff. You know you believe when you grow in obedience to God’s Word.