Loraine Boettner D.D.:
[S]hall we not believe that God can convert a sinner when He pleases? Cannot the Almighty, the omnipotent Ruler of the universe, change the characters of the creatures He has made? He changed the water into wine at Cana, and converted Saul on the road to
Damascus. The leper said, “Lord, if thou wilt, thou canst make me clean,” and at a word his leprosy was cleansed. God is as able to cleanse the soul as the body, and we believe that if He chose to do so He could raise up such a flood of Christian ministers, missionaries, and workers of various kinds that the world would be converted in a very short time. If He actually purposed to save all men, He could send hosts of angels to instruct them and to do supernatural works on the earth. He could Himself work marvelously on the heart of every person so that no one would be lost. Since evil exists only by His permission, He could, if He chose, blot it out of existence. His power in this latter respect was shown, for instance, in the work of the destroying angel who in one night slew all the first-born of the Egyptians (Exodus 12:29), and in another night slew 185,000 of the Assyrian army (2 Kings 19:35). It was shown when the earth opened and swallowed Korah and his rebellious allies (Numbers 16:31-33).
Ananias and Sapphira were smitten (Acts 5:1-11); Herod was smitten and died a horrible death (Acts 12:23). God has lost none of His power, and it is highly dishonoring to Him to suppose that He is struggling along with the human race doing the best He can but unable to accomplish His purposes. (The Reformed Doctrine of Predestination)