It was a little snarky because I find your premise to be ridiculous.
Rather than complaining about Japan not getting the "right brand" of Christianity because they were exposed to Christmas rather than what you believe is important - go to Japan and sell Jesus to them the way you want to. Not everyone that believes in Jesus agree on everything.
Right, the fake 'weed/tares' will Not agree with the genuine 'wheat' Christians.
Both grow together until the Harvest Time or the soon coming Time of Separation as found at Matthew 25:31-33,37.
If I was younger and you would pay my way (can't afford it ) I would gladly go to Japan.
It is Not that there are Not Christians in Japan, the good news of Matthew 24:14 is proclaimed there as it is here and elsewhere.
Missionaries have been sent to Japan for decades.
Exposure and accepting the Christmas lie appeals to the fake ' weed/tares ' form of Christianity ( aka Christendom )
I don't mean that as complaining but as scriptural fact.
Please notice the list of things God hates according to Proverbs 6:16-19 especially at verse 17.