Question

Why does the Christian need to have his or her mind renewed?

pleases help

Answer 1

So that he/she makes change the old way of thinking of God's way of thinking, and thus, be able to "prove what is that good and acceptable and perfect will of God" (Romans 12:2)

Answer 2

I believe the answer you are looking for is to be able to "prove what is that good and acceptable and the perfect will of God"