John recorded Jesus as saying.
I am the way the truth and the light, no man comes to the father but by me.

And then, when John was the last disciple standing he recorded Jesus fully empowered in Heaven as saying.

I, Jesus, have sent my angel to give you this testimony for the churches. I am the Root and the Offspring of David, and the bright Morning Star. And the Spirit and the bride say, Come. And let him that heareth say, Come. And let him that is athirst Come. And whosoever will, let him take the water of life freely.

And the conditions He put on that Whosoever were... exactly nothing. And it is His final word because it is the last thing in the book.

Oh, except that one last thing were He says that if anyone adds anything to what he says all the plagues will be upon them.

Gee... Come to think of it... Christendom does look a little poxish doesn't it?