10 Anyone who believes in the Son of God has this testimony in his heart. Anyone who does not believe God has made him out to be a liar, because he has not believed the testimony God has given about his Son. 11 And this is the testimony: God has given us eternal life, and this life is in his Son. 12 He who has the Son has life; he who does not have the Son of God does not have life.
The second part of verse 10 is interesting, for it seems to assume that everyone has a built-in knowledge of Jesus. There is an extent where God speaks through His creation and puts a level of hard-wired awe and respect for Him into even folks who haven't darkened a church door or even heard a sliver of the Gospel.
John would lead us to think that that level of knowledge gets to the point of being able to reject the Son of God that they might not have even heard of. That's heavy.
It might also answer the question that the more universalist among us would ask-"How can God send someone to Hell for not believing in a Messiah they never even heard of?" If this passage is any indication, they may have heard in their hearts if not in their heads. That might also give hope to those unreached folks who might have Jesus in their heart even if they haven't heard His name proclaimed.
That's not standard evangelical theology, which would lean towards that poor unreached person getting roasted for eternity; all the more reason to get off our butts, get out our checkbooks, and reach him, the missions sales pitch goes. This casts some doubt in that meme, but it's novel enough to not want to dive into without further thought; misreading a single passage can create some rather funky theology.