'Know' in the Bible

But we know that the law [is] good, if anyone makes use of it lawfully,

(but if someone does not know how to manage his own household, how will he take care of the church of God?),

But if I am delayed, [I am writing] in order that you may know how one must conduct oneself in the household of God, which is the church of the living God, the pillar and mainstay of the truth.

who forbid marrying [and insist on] abstaining from foods that God created for sharing in with thankfulness by those who believe and who know the truth,