There is an argument on-going on Facebook that started when the Amazon Kindle people wished everyone a Happy Earth Day. Some took great exception to that and declared that they would honor Good Friday instead.
Why can't we do both? I can thank my God for the sacrifice He made, sending His only Son to die for my salvation. And I think that one way we can show that gratitude is to show respect for the home given to us by our Father by conserving earth's resources and cleaning up our oceans.