Romans 8:6
“For to be carnally minded is death; but to be spiritually minded is life and peace.”
In the sermon, “A Thinking Man’s Filter”, Brother Branham explains what a “thinking man” is.  A thinking man is a person who is spiritually minded, living and walking in the mind of Christ. The best way to describe the first step to becoming a thinking man is to see that there are only two classes of people in the world: spiritually minded people and carnally minded people. In an early sermon, “The Great Commission” in 1957, Brother Branham explains, “And the lineage of—of Cain's children become scientists. The lineage of Seth's children was spiritual. Those two different classes of people exist today: scientists and spiritual-minded people.” To have life and peace from God is to have hope and purpose in this life. So then, the objective becomes clear, we search for the spiritual mind.
The spiritual mind is not something that we have great revelations of or come to by our own ability. It is simply our faith being placed and led into the Word of God by the Spirit of God. God operates on the basis of His Word, so because we are sons and daughters of God coming into our adoption, the Spirit of God leads us into His Word and expresses it through us. It is a supernatural thing, given and placed by a supernatural God. It really is that simple.
You must first have the right mind before you can be a thinking man. You must first come to the realization in your heart that you are Christ's, and His mind is in you, before you can discern what is right and wrong. When you have the mind of Christ, then anything contrary to the Word of God will not be an option, but a temptation. The mind of Christ leads you to life and peace. Let God place His mind in you.
To be spiritually minded is the first step to becoming a “thinking man”.
57-0901M - “Hebrews, Chapter Three”
There you are. Let the world say what they want to, and do what they want to do. Blessed be the Name of the Lord. Keep me in Christ, if I'm called anything… a fanatic, or holy-roller. Someday He's coming, and those that are in Christ will God bring with Him, when He comes. It's all a spiritual, revealed Truth laying right there, and it takes a spiritual mind to catch It. Rest on that, through the day. Think of it. Even if you do without your dinner, think of it.

Read the Bible in 1 year:
Acts 1-3