Well, nothing to them. We Baptists however, believe that we should as a matter of Christian practice, worship God in "spirit and truth". We can't Christianize idols for that reason. For similar reasons, I don't pray to Mary or the "saints". We have absolutely no scripture to support such a thing.
However, Paul says "One man esteemeth one day above another: another esteemeth every dayalike. Let every man be fully persuaded in his own mind. He that regardeth the day, regardeth it unto the Lord; and he that regardeth not the day, to the Lord he doth not regard it." (Romans 14:5-6a)
We have leave to celebrate whatever we wish as long as we celebrate unto the Lord.
Because the Lord says, "Love thy God and love thy neighbor as thyself", I don't celebrate Halloween by tossing my teen boys into the bog, because I don't want to be tossed myself, nor does God request me to sacrifice my children. I am NO LONGER IN BONDAGE. Therefore, I can hand out enough candy to fill a barrel and not worry about sin, I like candy, so I am treating my neighbors kindly and God has nothing but good to say about giving generously. I can even decorate my yard with fun but spooky decorations, because I KNOW who is in control and that I have nothing more to fear from death! Isn't that what the Good News is all about?