When a person is regenerated, he acquires a new will and a new understanding.
The present-day church is aware that, when a person is regenerated, he is renewed or becomes a new person; this is evident both from the Word and from reason. These passages from the Word prove this:
Make yourself a new heart and a new spirit; why will you die, o house of Israel? Ezek. 18:31.
I will give you a new heart and a new spirit in your midst, and I will take away the heart of stone from your flesh; and I will give you a heart of flesh, and I will put my spirit in your midst. Ezek. 36:26, 27.
From now on we know no one according to the flesh; so if anyone is in Christ, he is a new creature. 2 Cor. 5:16, 17.
A new heart in these passages means a new will, a new spirit means a new understanding. For heart in the Word stands for the will, and spirit, when linked with the heart, for the understanding.
The argument from reason is: when a person is regenerated he has a new will and a new understanding because these two faculties are what make him a human being, and it is these which are regenerated. Everyone, therefore, is such as he is in these two respects. If his will is evil, he is evil, and the more so if his understanding favours evil; and the reverse is true, if his will is good. It is only religion which renews and regenerates a person. Religion is allotted the highest place in the human mind, and sees below it the social matters which concern the world. Religion too climbs up through these as the pure sap rises in a tree to its top, and from that lofty position it has a view of natural matters, just as someone on a tower or a mountain has a view of the plains beneath.