God’s call is irresistible in the sense that it can overcome all resistance. It is infallibly effective according to God’s purpose – so much so that Paul can say, “Those whom God called he also justified.” In other words, God’s call is so effectual that it infallibly creates the faith through which a person is justified. All the called are justified. But none is justified without faith (Romans 5:1). So the call of God cannot fail in its intended effect. It irresistibly secures the faith that justifies.