I may certainly express my beliefs of a religious practice that believes only in the here and now. I am familiar with the emptiness and unfulfilling character of a person who beleives that now is the only existence and that our only future is to be eaten by worms. If that can sustain you, more power to you. But Christians have a better way. Christians know that there is a better world beyond this one.
Of course you "may" express your beliefs. And if you think Christians have a better way, I'm happy for you. Sing it out man! But if in your desire to promote your faith, you try to leverage off of another by degrading it, you make an jerk of yourself.
I could rip into your faith with all the viciousness that you've just done to that of most Jews, but that would be counter productive. Doing so pits good men against one another and causes the best of them to think less of the one causing trouble, even some that share his faith or ideology.
If you find that you cant' stop this behavior, I'm sure the problems not with others.
I used to be a Christian. I can honestly say that my life has never been more full than it is now.