God, through Scripture, says he has called you out of darkness into his wonderful light (1 Peter 2:9). The idea is very similar to that moment in the Matrix when Neo gets the package with the ringing phone and a series of amazing events unfold. The doctrine of effectual calling should be kept separate from the doctrines of Apologetics and Evangelism because it's personal, because it's about the election of particular people, those he predestined, he also called (Rom 8:30). "Effectual calling" is also ultimately successful, for God’s gifts and his call are irrevocable (Rom 11:29). It's not as though God makes someone an offer and they decide whether or not to buy Amway but God brings supernatural force to bear on their situation and the person begins a radical new direction in their life's journey. The most useful aspect of this doctrine is the way it describes the pull God exerts and introduces into your life. For some it's as simple and dramatic as hearing someone else ask them to become a Christian, for others it's more of a series of small events, circumstances and comments that nudge you towards repentance and faith. Finally this doctrine is useful for Christians thinking about and describing how they became Christians.