Berrigan taught others to shirk their Christian moral duty to protect innocent people against deadly attack by unjust aggressors.  He was no prophet.  He preached a false Christianity.  He taught a foolish Christianity --- that it was wrong for this country to have an army --- and was thereby a detriment to the Church.  

As for the "If a man strikes you on the cheek, . . ."
5:38-42 The plain instruction is, Suffer any injury that can be borne, for the sake of peace, committing your concerns to the Lord's keeping. And the sum of all is, that Christians must avoid disputing and striving.  

I don't disagree about that.   But Berrigan wasn't talking about "suffering any injury that can be borne."  He taught absolute pacifism --- allowing others to suffer not just a slap on the cheek, but deadly aggression.