Before a person can be saved he must, of course, know about sin and salvation and must give mental assent to what the Bible says about these things. He must agree that Christ died for man’s sins.
But while intellectual faith is a good start, it is not enough to save you. You must go on from there to trust yourself to Christ, who died for our sins (I Cor. 15:3), otherwise your intellectual faith has done you no good.
God wants our heart trust; it is this kind of faith that honors Him, and it is this kind of faith that saves. In Romans 10:9-13 He says:
“If thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised Him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. For the Scripture saith: Whosoever believeth on Him shall not be ashamed… For whosoever shall call upon the name of the Lord shall be saved.”
If Christ is not a risen, living Savior, He is no savior at all. We must believe this in our hearts if we are to call upon Him for salvation.
Thank God that “He showed Himself alive, after His passion, by many infallible proofs” (Acts 1:3) and that millions have indeed found the peace and joy of sins forgiven through faith in the Lord Jesus Christ and His redemptive work at Calvary. source