Moshiach
The topic of Moshiach is on the one hand the most fundamental of all Jewish beliefs, and at the same time, it is also one of the most controversial. The notion that the world has a destiny, that it was created with a purpose to achieve and an end-game when it will be achieved, goes hand in hand with the belief in Hashem that there is meaning and purpose to reality. This negates the notion that the here and now is all there is-the universe doesn't just exist, it exists with a purpose, and Moshiach is that purpose.