- It's a very happy religion. God is good, god loves you unconditionally, god wants you to live forever in paradise with him, and (depending on your brand on Christianity) it's often very easy to assure that you will. People like to believe in things that make them feel good.
I think a better view of this point would go something like "It is a religion that can be whatever you want it to be". The fundamentals are sound, the whole peace, hope, helping others, etc, but you can flavour it however you please.
Are you into the wrathful eye for an eye, god is testing you and you'll burn in hell if do naughty things in the night? Well my friend, you'll want the
Old Testament, and heap it on.
Want love, peace, and help thy neighbour? The
New Testament is your friend.
Want a bit of both? Cherry pick as you please from all the different books and make it as you like. Christianity is an all you can eat, make your own Sundae Bar. They all have the same basic idea behind them, but some people just go with more nuts than others.
And of course, is the Christian Bible not enough for you to get what you really want in a religion? Then add your own extensions and traditions!
Christianity is like Linux in the Religious world. It comes in all sorts of flavours, some are more popular than others, and it is fairly easy to customize it to your own idea of what it should be. If you really know what you're doing then your version can take off. If you're bad at it, then you'll be labelled as a cult.