Ok, you and xenocles appear somewhat baffled; I'm not sure why, most people I show it to seem to understand right away.
What the meme comments on is how easy it would have been for Jesus - or, more specifically, the Gospel's accounts of Jesus' words - to put the issue to rest. With but a sentence, the Bible could have directly and explicitly addressed whether homosexuality is indeed a sin or not, which would have avoided an enormous amount of contention and debate in the two thousand years that followed. Without it, we have been forced to cite other passages of the Bible - for example, projecting from the wording of Jesus' views on adultery and remarriage; or citing from the legal system of a desert nomad nation; or building from the letters of St Paul, who comes with his own list of issues.
Given the importance that the subject has taken since Jesus' time, it seems a glaring omission that the Gospel wouldn't take the time to give homosexuality a direct and explicit thumbs up or down. (I know! Please wait.)
There are a couple of reasons this could be. It COULD be that Jesus quite literally never breathed a word on the subject, that the idea of a same-sex marriage was just that fantastic that it would make little sense to address it. Most people, though, would agree that this is unlikely: among other things, Jesus was known to dine and socialize with "sinners" - the marginalized of society, your thieves, your hookers, what have you - so it seems most unlikely that in all his Ministry, nobody took the time to ask "hey, since we're on the subject of sin, what's the deal with gay people"?
So the other possibility is that he did say it, but it was never written down when the Bible was authored, edited, and compiled - which started about fifty years later and wasn't really finalized until the emperor Constantine - plenty of time for the openly homophobic Roman Empire to shoehorn their politics into the editing process.
I KNOW that you are certain that the Bible DOES specifically and directly classify homosexuality as a sin - but it IS a point of contention in the wider Christian community (I KNOW! Ok, we all know where you stand - but it's an ongoing debate. Don't take that up with me, write to the holdouts in the Christian churches who disagree with you about it) and the meme uses this to give people a thinker as to why it's not more easily settled.
People find it clever and funny, snarky but not arrogant. It's a meme. What else do you want?