"Brothers and sisters, stop thinking like children.... [I]n your thinking be adults" (1 Corinthians 14:20). Why isn't that ever the memory verse?
God made us rational beings. That's part of being made in his image. And -- in the Bible -- he's given us a rational revelation of himself and his will which he obviously intended for us to study.
Furthermore, every aspect of Christian discipleship depends on our willingness to think and reflect upon God's glory, God's faithfulness and God's desire for our lives.
Finally, like the earliest apostles, we are called to not only "preach" the gospel but to "defend" and "argue" it so as to "persuade" people of its truthfulness (cf. Acts 17; 19:8; 2 Corinthians 5:11; Philippians 1:7).
I don't know if you've ever thought about this or not, but, in the Old Testament, the great declaration of faith of God's chosen people was Deuteronomy 6:4-5: "Hear, O Israel: The Lord our God, the Lord is one. Love the Lord your God with all your heart and with all your soul and with all your strength."
But when Jesus lived on earth, someone once asked him to recite this great command, and Jesus made an interesting addition. Jesus quoted it, "Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength" (Mark 12:30).
So, either Jesus misquoted the text, or he thought it was important enough to add the bit about loving God with all your mind.
What are some other reasons why you think it might be important to love God with all your mind?