Why is our physical world so different from spiritual?

I read this comment from one of the answers: > As we are only mortal flesh, we are not capable of understanding the > unique nature of God. Jesus also many times found it difficult to > explain about God and Heavenly things. It's like trying to explain how > a computer works to the elderly people who are not familiar with it. > Once I tried to explain how a computer works to my father, it was > impossible and I gave up. My question is: According to the Roman Catholic Church why is our world so different from the spiritual one and how that difference servers Gods plan for us? Our life in this physical world should serve as a gateway to the spiritual realm after we die but if it's so different how that can serve the purpose.