By Him everyone who believes is justified from all things from which you could not be justified by the law . . . (Acts 13:39)
To say that we believe in Christ and yet do not believe in the things that He says is at best a very questionable belief. For example, Jesus said: "You shall not tempt the Lord your God,"(1) "You shall worship the Lord your God,"(2) "Follow Me,"(3) "If you abide in My word, you are My disciples indeed,"(4) "It is more blessed to give than to receive."(5) To say that we believe in Jesus and not desire to yield to His authority is not to believe in Him at all.
It is not a matter of works; it is a matter of believing. Don't tell me you believe in Jesus, but that you are not willing to walk in obedience to Him. Jesus also said, "If you love Me, keep My commandments."(6) Belief in Christ cannot be separated from obedience to Christ. To attempt to do so is to malign the meaning of biblical belief.
(1) Matthew 4:7, (2) Matthew 4:10, (3) Matthew 8:22, (4) John 8:31, (5) Acts 20:35, (6) John 14:15