I am really trying to stay away from interdenominational debates, for the sake of courtesy and diplomacy. But you aren't making things any easier. I will still try to address it without getting into into disputes, though.
First. The Bible also says: "For just as the body without the spirit is dead, so also faith without works is dead" (James 2:26). The consequence of having a honest faith is living it, works are a natural consequence here, not the reason of salvation. Conversely, we can conclude that someone who says to be a Christian, but don't practise it, is a liar. Heck, the Bible even says something in these lines: "Whoever claims to love God yet hates a brother or sister is a liar. For whoever does not love their brother and sister, whom they have seen, cannot love God, whom they have not seen." (1 John 4:20).
I think we already went through this: the demons of Hell know that God exists, so this by itself should suffice to let clear that just believing in God is not the enough. You speak like just believing and nothing else should suffice. Be careful, you are oversimplifying things. There is much more to the Christian faith than "rejoicing". It is not supposed to be a walk in the park, the faith is called "the narrow path" for a reason, you have to pick your cross and follow Christ. And carrying the cross is not exactly a party.
Second. I have learned that replying to some unfounded accusation gives some validity to it. If someone asks "Have you stopped beating your wife?", I will be compromising myself no matter what I answer, even if I say "yes" it implies that I have beaten the wife at some point. That is why I will not even address that the Catholic Church supposedly does not worship God enough.