Salam,
I know that Allah doesn't like pagan traditions and so I am thinking can we even wish someone a Merry Christmas, Happy Holidays or Season's greetings if they greet us with this? Is this 'bidah' (innovation)?
What happens when someone invites us to attend a Christmas party? I haven't come across this yet but i feel that I should decline because I feel that this may cause my Lord to be upset because in a way, it is going against Him.