The Greek adjective asunetos means without understanding, unintelligent, or foolish — lacking the capacity or willingness to perceive and apply truth. It is the negation of sunetos (intelligent, insightful) and describes a darkened mind unable to grasp spiritual reality.
Paul uses asunetos in Romans 1:21 as part of his diagnosis of Gentile idolatry: 'their thinking became futile and their foolish hearts were darkened.' Suppressing the knowledge of God actively corrupts the mind's capacity for right understanding — it is not neutral. Jesus mourned the asunetos disciples who failed to perceive the significance of His miracles (Mark 7:18). The antidote is the mind renewed by the Holy Spirit — the mind of Christ (1 Corinthians 2:16), which understands the things freely given by God.