Why saving grace must be irresistible

The fourth point of Calvinism is Irresistible Grace.  This doctrine says that when God calls us to faith in Jesus he calls effectively; he always succeeds in his purpose to save us.

The Bible distinguished between the general call of God to all sinners to come to Jesus (e.g. Jesus saying “Come to me, all you who are weary and burdened, and I will give you rest”) and the specific call or summons God gives to his elect (e.g. Romans 1:6…you also are among those who are called to belong to Jesus Christ…)