There are certainties only adults need to understand, such as we will die. However, my close friend's three little girls understand this following his early death.

The certainty that kids require is to know know they are loved and provided for.

As humans we all have to chose at some stage a worldview that believes we are material objects or there is a God. I have chosen the latter and brought my children up with the knowledge of the Bible. I am certain God is with me, this life will have challenges, and I will go to a better place when I die.