A question was asked in Acts 16:30, “What must I do to be saved?”
The answer was, “Believe on the Lord Jesus Christ, and thou shalt be saved.”
But what is it to believe?
It is to put your whole trust and faith in the Lord Jesus.
But what is faith?
Faith, saving faith, consists in your believing that Jesus Christ came to seek and to save the lost. It is believing in the good news of a complete salvation in Him and a firm trust in God that He will fulfill all His promises. “He that cometh to God must believe that He is, and that He is a rewarder of them that diligently seek Him” (Heb. 11:6).
It is not just believing with the head-that is, mentally. Hear God’s own Word on the subject: “The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith...that 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” (Rom. 10:8-10).
This is saving faith. It is not trusting to services, rituals or sacraments, but it is coming to the Lord Jesus Christ Himself who said, “I am the way, the truth, and the life: no man cometh unto the Father, but by Me” (John 14:6).
In other words, saving faith believes what God has said. “These are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life though His name” (John 20:31).
BUT: “He that believeth not God hath made Him a liar; because he believeth not the record that God gave of His Son” (1 John 5:10).