(Yes, I know these folks don't represent ALL Christians, but neither do the articles on atheists and agnostics posted here represent all of us non-believers.)
For these people to call themselves "Christian" is violating the commandment against taking the name of the LORD your God in vain.
""I tell you most solemnly, whoever keeps my word will never see death."
(Jn.8:51). ""You must not love this passing world or anything that is in the world. The love of the Father cannot be in any man who loves the world...because the world, with all it craves for, is coming to an end..." (1 Jn.2:15-17).
""After I have gone and prepared you a place, I shall return to take you with me..." (Jn.14:3).