wish

Wishing someone merry christmas

Q: If a Muslim wished someone merry christmas will he have become a kafir, because in modern times christmas is just another cultural money making thing and people do not know the reality of christmas that it is the celebrating of jesus birthday and therefore if a muslim said merry christmas at a time without realising at the time the consequence and value of what he was saying he merely just said it out of respect or he said it but out of regret then will he become a kafir at that point? Because a muslim could have said the words merry christmas but with regret in his heart, obviously one understands to not do such a thing again but will he have become kafir for saying this without truly meaning it ?