Are these the words of Jesus or a narrative that was added?

I have heard that many bible scholars agree that these verses are not what Jesus said; just wanted to clarify this.

John 3:16 - 21

ESV - ¹⁶ For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. ¹⁷ For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him.

Clarify • Share • Report • Asked March 28 2015 • Tim Collinson