John 3:18

“He who has believed and has been baptized shall be saved; but he who has disbelieved shall be condemned.

But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name,

No one has seen God at any time; the only begotten God who is in the bosom of the Father, He has explained Him.

“For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life.

“Truly, truly, I say to you, he who hears My word, and believes Him who sent Me, has eternal life, and does not come into judgment, but has passed out of death into life.

So we see that they were not able to enter because of unbelief.

And this is His commandment, that we believe in the name of His Son Jesus Christ, and love one another, just as He gave a commandment to us.

The one who believes in the Son of God has this witness in himself. The one who does not believe God has made Him a liar, because he has not believed in the witness which God has borne witness about His Son.