I'm gonna try to give an explanation using both science and religion. We don't understand what gravity is. We know it pulls us to the ground, we know it exists, we know it's what keeps everything stuck to the earth, but we don't know what it really is or why it works, it just works. Physics aims not to explain gravity, but to define it. Now let's look at, say, the Bible. It is stated in the Bible that God created life, the earth, and man in 6 days. Science isn't sure how we got here, it just knows that we are here. Science aims to define the natural world and religion aims to explain the natural world.
Both science and religion try to answer the question 'why'. Religion says 'a God did it!'. Science says 'I don't know. Let's observe our environment and see what theory could best explain what we see. If anyone later proves me wrong, I won't be upset, I will be glad that I understand more.'