He never said anything about the Japanese being atheist. It clearly states on the last sentence of the paragraph he says "I am talking about foreigners not Japanese people"

I didn't say Japanese people, I clearly said PEOPLE IN JAPAN. He said a lot of foreigners living in Japan hate religion. Most of them go to Japan because it's a generally non-religious country.

He Is free to write what he wants, no one should dictate to him what to write ,The existence of atheists in Japan doesn't mean that people can't exercise their religion's rights in japan .
Please do not start a religious talk.
Welcome.