IN WHOM MUST ONE BELIEVE TO BE SAVED?

All who believe will be saved!  Believe what?  Believe the Word of the Lord! 

1)  There is a God before whom all will stand in judgment; Revelation 20:11-13 says,

"And I saw a great white throne, and Him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them.  And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works.  And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works."

2)  God does not want any to be cast into the Lake of Fire.  2 Peter 3:9 says,

"The Lord is not slack concerning His promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance."

3)  God offered mankind an opportunity to be saved; He provided a substitute to pay for our sins:

"And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up:  that whosoever believeth in Him should not perish, but have eternal life.  For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have everlasting life" (Jn. 3:14-16).

4)  Before Jesus died for our sins, He pleaded with people to trust His Father:

"Verily, verily, I say unto you, He that heareth My word, and believeth on Him that sent Me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life" (Jn. 5:24).

5)  Yes, we are to believe that God, the Father of Jesus, sent Him to die for us:

"...This is the work of God, that ye believe on Him whom He hath sent" (Jn. 6:29).  "And this is the will of Him that sent Me, that every one which seeth the Son, and believeth on Him, may have everlasting life: and I will raise him up at the last day" (Jn. 6:40).

6)  The Father sent His Son to die, but He also raised Him from the dead:    

"...Believe on him that raised up Jesus our Lord from the dead" (Rom. 4:24).  "But God raised him from the dead" (Acts 13:30).

7)  To be saved then, one must trust in both the Father and in His Son:

"Let not your heart be troubled: ye believe in God, believe also in Me" (Jn. 14:1).  "...This is the work of God, that ye believe on Him whom He hath sent" (Jn. 6:29).  "I and My Father are one" (Jn. 10:30).