The scripture has to be taken as a complete work. It is possible to quote one verse to prove a point but not have the correct idea.
There are many verses that talk about believing and salvation. It's not one verse, it is many verses. The apostles were teaching saved by grace through believing in Jesus.
John 3:15
So that everyone
who believes will have eternal life in Him.
John 3:16
For God so loved the world, that He gave His only Son, so that everyone
who believes in Him will not perish, but have eternal life.
John 3:18
The one
who believes in Him is not judged; the one who does not believe has been judged already, because he has not believed in the name of the only Son of God.
John 3:36
The one
who believes in the Son has eternal life; but the one who does not obey the Son will not see life, but the wrath of God remains on him.”
John 5:24
Truly, truly, I say to you, the one 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.
John 6:35
Jesus said to them, “I am the bread of life; the one who comes to Me will not be hungry, and
the one who believes in Me will never be thirsty.
John 6:40
For this is the will of My Father, that everyone who sees the Son
and believes in Him will have eternal life, and I Myself will raise him up on the last day.
John 6:47
Truly, truly, I say to you, the one
who believes has eternal life.
John 7:38
The one
who believes in Me, as the Scripture said, ‘From his innermost being will flow rivers of living water'.
John 11:25
Jesus said to her, “I am the resurrection and the life;
the one who believes in Me will live, even if he dies,
John 11:26
And everyone who lives
and believes in Me will never die. Do you believe this?
John 12:44
Now Jesus cried out and said, “The one who believes in Me, does not believe only in Me, but also in Him who sent Me.
John 12:46
I have come as Light into the world, so that no one who believes in Me will remain in darkness.
John 14:12
Truly, truly I say to you, the one who believes in Me, the works that I do, he will do also; and greater works than these he will do; because I am going to the Father.
1 Corinthians 1:21
For since in the wisdom of God the world through its wisdom did not come to know God, God was pleased through the foolishness of the message preached to save those who believe.