Mk 16:16, Jn 4:25-26,

Jesus revealed himself to be the Christ through His ministry. (Jn 8:25, Jn 4:25-26)

Jn 8:25 Then said they unto him, Who art thou? And Jesus saith unto them, Even the same that I said unto you from the beginning.

Jn 4:25 The woman saith unto him, I know that Messias cometh, which is called Christ: when he is come, he will tell us all things. 26 Jesus saith unto her, I that speak unto thee am he.

If a person does not believe that Jesus is the Christ, he will die for sin. (Jn 8:24, Mk 16:16)

Jn 8:24 I said therefore unto you, that ye shall die in your sins: for if ye believe not that I am he, ye shall die in your sins.

Mk 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.