One of the teachings of evangelical Christianity is that faith in Jesus as your savior is the only thing that is required to be saved from your sins and go to heaven. This was taught by the Apostle Paul in his writings to the churches he helped found.

https://www.biblegateway.com/passage/?search=Ephesians%202&version=KJV

Ephesians 2: 8-9

⁸ For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:

⁹ Not of works, lest any man should boast.

But this is contradicted by what the Apostle John wrote in the book of Revelation.

https://www.biblegateway.com/passage/?search=Revelation%2020&version=KJV

¹¹ 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.

¹² 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.

¹³ 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.

¹⁴ And death and hell were cast into the lake of fire. This is the second death.

¹⁵ And whosoever was not found written in the book of life was cast into the lake of fire.

And Jesus himself said:

https://www.biblegateway.com/passage/?search=Matthew%207&version=KJV

²¹ Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.

²² Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?

²³ And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.

Considering that Jesus was the one that founded the Christian religion, and John was a disciple of his from the start, it is clear that Paul, who only claimed to be an Apostle long after the time of Jesus, was a false teacher. He never should have been accepted as a legitimate Christian!

And yet he was able to corrupt the New Testament, and then all of Christianity itself, forever!