Who are you to say this? To anyone that sees the tree as being idolatrous it is sin, and if this stumbles your brother or sister, then you would also stop it for the sake of your brother or sister. Yes, an idol is nothing. It is not possible during this time to go out to a restaurant or some other place and for there to be these idols up. I don't leave a restaurant because they have a Santa or a tree. But for a church to put these up? For a brother or sister to put these up? Only the Lord can judge, not you and not me. However, you have been told clearly that yes, these are idols and yes, they offend many brothers and sisters. What you do with that knowledge is between you and the Lord.There is nothing wrong with having a tree. But if you don't wish to have one, plenty of people celebrate Christmas without a tree. Santa, same thing.
1 Corinthians 8:4 As concerning therefore the eating of those things that are offered in sacrifice unto idols, we know that an idol is nothing in the world, and that there is none other God but one. 5 For though there be that are called gods, whether in heaven or in earth, (as there be gods many, and lords many,) 6 But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him. 7 Howbeit there is not in every man that knowledge: for some with conscience of the idol unto this hour eat it as a thing offered unto an idol; and their conscience being weak is defiled.
So you may be at work and they have a Christmas party with a tree and Santa and food. You can go to that party. You work there, you have been sent into the world to preach to the world, and to say you can't eat their food because it is offered to an idol would be similar to Peter not being able to eat with the Gentiles.
1 Corinthians 8:8 But meat commendeth us not to God: for neither, if we eat, are we the better; neither, if we eat not, are we the worse.
When I was in Taiwan you often went into a restaurant or home with an idol in the corner of the room. It was similar to a Christmas tree, only smaller. They would have their idol with some incense burning and some gifts (food) that was being blessed, just like a Christmas tree, candles and the gifts under the tree.
9 But take heed lest by any means this liberty of yours become a stumblingblock to them that are weak.
But just because I didn't have any problem eating with that idol in the same room doesn't mean I am going to set that idol up in my own home.
10 For if any man see thee which hast knowledge sit at meat in the idol's temple, shall not the conscience of him which is weak be emboldened to eat those things which are offered to idols; 11 And through thy knowledge shall the weak brother perish, for whom Christ died?12 But when ye sin so against the brethren, and wound their weak conscience, ye sin against Christ. 13 Wherefore, if meat make my brother to offend, I will eat no flesh while the world standeth, lest I make my brother to offend.