Every religion emphasizes human improvement, love, respect for others, sharing other people's suffering. On these lines every religion had more or less the same viewpoint and the same goal.
The year showed me beyond a doubt that everyone practices cafeteria religion... But the important lesson was this: there's nothing wrong with choosing. Cafeterias aren't bad per se... the key is in choosing the right dishes. You need to pick the nurturing ones (compassion), the healthy ones (love thy neighbor), not the bitter ones.
If you are angry you will share anger, if you are greedy you will share greed, if you are full of lust you will share your lust. We can share only that which we have, we cannot share that which we don't have. This has to be the fundamental thing to be remembered; hence the first step is meditation and the second step is compassion.
Great Powers of falling wave and wind and windy fire,
With your harmonious choir
Encircle her I love and sing her into peace,
That my old care may cease.
Ultimately, the reason why love and compassion bring the greatest happiness is simply that our nature cherishes them above all else. The need for love lies at the very foundation of human existence.