This is not the kind of thing the Buddha said. He didn’t say there was no god. In the scriptures he’s depicted as talking with gods, although those passages may be intended to be taken humorously.
There’s one rather hilarious (by 2,500-year-old standards) passage where a monk is depicted as having worked his way up through all the lesser gods to the Great Brahma himself, asking where the four elements come to an end. Brahma blusters, declaring over and over how he is all-knowing. The monk calls him on his BS, and eventually Brahma takes him to one side, confesses that he doesn’t want the other gods to know that there are things he doesn’t know, and tells the monk to go see the Buddha, who is the only one who can answer his question.
He did ridicule the idea of a creator god, depicting Brahma as having deluded himself into thinking he had created the universe and the other gods. I tend to take that as an allegorization of mamankara, or “mine-making” which is the way that part of us deludedly thinks that it owns and is responsible for other parts of us, including our thoughts, feelings, and actions.
He criticized the idea that our suffering is due to the actions of gods and said that if this were the case, then god must be evil.
He certainly wouldn’t have said that “only this world is true.” He’s depicted as talking about rebirth in other realms, including hells and heavens.
The URL in the image doesn’t lead to an existing Facebook page. Possibly at some point the Bharatiya Yukthivadi Sangham organization had one, and it was removed. The Yukthivadi Sangham is a rationalist and humanist organization in India. Bharatiya means “Indian” so I assume that this is a national organization. I’m surprised they don’t have a Facebook page. Or maybe I just failed to find it.
It’s interesting that a rationalist organization is using the Buddha (in the form of a fake quote) to argue against theism. Despite this, I wish them well as they work to combat the influence of religion on Indian politics and society.