Matthew 13:31-35 - "The Parables of the Mustard Seed & The Leaven"

The Christian cannot be satisfied so long as any human activity is either opposed to Christianity or out of all connection with Christianity. Christianity must pervade not merely all nations, but also all of human thought. The Christian cannot therefore be indifferent to any branch of earnest human endeavor. It must all be brought into some relation to the gospel. It must be studied either in order to be demonstrated false or else in order to be made useful to the kingdom of God. The kingdom must be advanced not merely extensively, but also intensively. The church must not only seek to conquer every man for Christ, but also the whole of the man." – J. Gresham Machen