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 (Romans 10:9).
There is a popular Christian song whose chorus ends with these words: You ask me how I know He lives; He lives within my heart. This may sound spiritual, but this is not how we know He lives! We are saved because He died for our sins and then rose bodily from the tomb, triumphant over sin, death, the curse, and Satan, alive in His glorified body, forevermore. It is this which we must believe in our hearts and confess with our lips. For Him to rise bodily from the grave means that He is nothing less than God, the very Creator Himself. It is only because of who He is that He could do what He did, and this is what we must believe in our hearts.
There are people who believe that Buddha lives in their hearts, or the spirit of the gods indwells their hearts, or even that the Christ is in their hearts, but the heart is deceitful above all things (Jeremiah 17:9). We can believe many things, and feel many things that are not so. We know Jesus Christ is a living Savior, not because we feel His presence in our hearts, but because He rose from the grave on the third day and shewed Himself alive after His passion by many infallible proofs, being seen of them forty days (Acts 1:3). The gospel of our salvation does not rest on our feelings, nor on someones teachings, but on the objective, proven, certain facts of history. Jesus Christ is alive, whether anyone feels Him living in their hearts or not, and He is at this moment bodily in heaven, at the right hand of the Father (e.g., Romans 8:34).
Wherefore, He is able also to save them to the uttermost that come unto God by Him, seeing He ever liveth to make intercession for them (Hebrews 7:25). HMM