The glory of God is a human being fully alive. - St. IrenaeusIn this life, we could decide that the world doesn't matter at all and that we should be wholly spiritual. We would become entirely of God but not of the world, and we would be missing something.
We could decide that the world is everything and there is no God. We would become entirely of the world - materialistic - and ignore God or proclaim He doesn't exist. We would again be missing something.
By bringing both together, by living in God and in the world, we become fully alive. This world and everything in it is ultimately God's creation. That makes the world inherently good and worthy of our attention, our care, and our love. But it is not worthy of our worship, because the world is not God. God deserves our worship, and we are only fully alive - fully human - when we live the reality of God *in the world* seven days a week, instead of just an hour on Sunday.