Our faith is what saves us. Ephesians 2.8 tells us that we are saved by grace through faith. God has ordained us unto good works, so those who are saved through faith will manifest those good works (the fine linen with which the saints are clothed represents the righteous acts of the saints). "REV19.7 Let us be glad and rejoice, and give honour to him: for the marriage of the Lamb is come, and his wife hath made herself ready. REV19.8 And to her was granted that she shouldbe arrayed in fine linen, clean and white: for the fine linen is the righteousness of saints."
I have heard several preachers say that we are saved through faith and faith alone. I think we are saved through faith which is evidenced by good works. Even devils believe that there is one God, so if that's the sort of faith you're thinking of, that might not cut it. Jesus warns us in Matthew chapter 7 that he will reject those who continue in their sinfulness while claiming to serve him: "MAT7.21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven. MAT7.22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? MAT7.23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity."
We cannot say that we have faith and we believe God, but totally disregard his teachings. "JAM2.14 What doth it profit, my brethren, though a man say he hath faith, and have not works? can faith save him? JAM2.15 If a brother or sister be naked, and destitute of daily food, JAM2.16 And one of you say unto them, Depart in peace, be ye warmed and filled; notwithstanding ye give them not those things which are needful to the body; what doth it profit? JAM2.17 Even so faith, if it hath not works, is dead, being alone. JAM2.18 Yea, a man may say, Thou hast faith, and I have works: shew me thy faith without thy works, and I will shew thee my faith by my works. JAM2.19 Thou believest that there is one God; thou doest well: the devils also believe, and tremble. JAM2.20 But wilt thou know, O vain man, that faith without works is dead? JAM2.21 Was not Abraham our father justified by works, when he had offered Isaac his son upon the altar? JAM2.22 Seest thou how faith wrought with his works, and by works was faith made perfect? JAM2.23 And the scripture was fulfilled which saith, Abraham believed God, and it was imputed unto him for righteousness: and he was called the Friend of God. JAM2.24 Ye see then how that by works a man is justified, and not by faith only."
So, in summary we are saved by faith. The evidence of faith is good works in the life of the believer. We are called to be a light unto world. If you are a believer, the world must see the light in you and glorify your Father in heaven. "MAT7.17 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. MAT7.18 A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. MAT7.19 Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. MAT7.20 Wherefore by their fruits ye shall know them."