What new nature does God place in a believer?
At salvation, God places opposite the old Adamic nature a new nature—a new divine nature. Because it is divine, this new nature cannot sin. When believers sin, it is the old Adamic nature momentarily taking control, not the new divine nature placed within them.
Les explains from Galatians 5:17 that the believer has two natures. The old sin nature—the old Adam we are born with—had to be crucified and put to death in the realm of the Spirit when we believe the Gospel, and Christ reckons it as crucified. Immediately God places opposite that old Adamic nature a new nature, a new divine nature. Les maintains that this new nature cannot sin because it is divine. When believers sin, it is simply the old Adam taking control for a moment, and it is through the old nature that they continue to sin. In God's eyes, old Adam is dead, so He can declare us justified, as if we had never sinned.