Eternal Sanatan law
Everything that is created in this world has one limitation: time, duration. You may call it life or existence. Even a stone has a life. After a certain time, that stone will be melted, powdered or destroyed. There is eternal Sanatan law, Sanatan Dharma. It says: who has come, has to go. Who received it, has to give it over. Who was born will die; what is created will be destroyed; what is manifested will disappear. So, everything has its time.
Now, what is the purpose of this all?
Development of consciousness; to come back to the origin again, because we are separated and feel like individuals. We feel lonely, happy or unhappy, pleasure or pain; we feel separated and we are struggling for our survival. But, there will come the day to come to one-ness again, when all of this will end. This is the purpose of developing consciousness, so the individual spirit will become one with Divine Spirit, what is also called the Holy Spirit. This Holy Spirit means the entire Universe. So, we have to develop into that One.
When you are born as a human, you have already reached the level of that pure spirit but our karma can push us back or bring us forward. Increasing or decreasing - it depends on our work.