One of the places in Scripture that teaches effectual calling (irresistible grace) and the sovereignty of God in regeneration is Acts 16:14, where Luke writes this about Lydia: “The Lord opened her heart to respond to the things spoken by Paul (NASB).” I appreciate Richard Sibbes’ comments on this text:
“…As our hearts are shut and closed up naturally, so God, and God alone, opens the heart, by his Spirit in the use of the means. God opened Lydia’s heart.
God hath many keys. He hath the key of heaven to command the rain to come down. He hath the key of the womb; the key of hell and the grave; and the key of the heart especially. ‘He opens, and no man shuts; and shuts and no man opens’ (Rev. 3:7). He hath the key of the heart to open the understanding, the memory, the will, and affections. God, and God only, hath the key of the heart to open that. It is his prerogative. He made the heart, and he only hath to do with the heart. He can unmake it, and make it new again, as those that make locks can do. And if the heart be in ill temper, he can take it in pieces, and bring it to nothing as it were, as it must be before conversion; and he can make it a new heart again.
It is God that opens the heart, and God only. All the angels in heaven cannot give one grace, not the least grace. Grace comes merely (only) from God. It is merely (only) from God. All the creatures in the world cannot open the heart, but God only by his Holy Spirit. For nature cannot do above its sphere, as we say, above its own power. Natural things can do but natural things. For nature to raise itself up to believe heavenly things, it cannot be. Therefore as you see vapors go as high as the sun draws them up, and no higher, so the soul of man is lift up to heavenly things by the power of God’s Spirit. God draws us and then we follow. God, I say, only openeth the heart.
Covenant Presbyterian Church