Faith is not a work, or works. We are saved by faith and not by works. It is not the ‘act of believing’ which was credited to us for righteousness and justification. It is faith itself which is credited for righteousness. A faith seed given initially by God through His Word, grown in the heart by his ‘increase,’ and then exchanged for His righteousness.
Don’t confuse diligence and obedience with our own self works.