God's Unchanging Justice And Love
Illustration★★★If God be immutable, it is sad news to those that are resolved in wickedness, or careless of returning to that duty he requires. Sinners must not expect that God will alter his will, make a breach upon his nature, and violate his own word, to gratify their lusts. No, it is not reasonable God should dishonor himself to secure them, and cease to be God, that they may continue to be wicked, by changing his own nature, that they may be unchanged in their vanity.
God is the same; goodness is as amiable in his sight, and sin as abominable in his eyes, now, as it was at the beginning of the world. Being the same God, he is the same enemy to the wicked, as the same friend to the righteous. He is the same in knowledge, and cannot forget sinful acts. He is the same in will, and cannot approve of unrighteous practices.
Goodness cannot but be alway the object of his love, and wickedness cannot but be alway the object of his hatred; and as his aversion to sin is alway the same, so as he hath been in his judgments upon sinners, the same he will be still; for the same perfection of immutability belongs to his justice for the punishment of sin, as to his holiness for his disaffection to sin. Charnock.
— Charnock
The point
Charnock argues that because God is immutable, sinners cannot expect Him to change His nature or word to accommodate their sin -- His holiness and hatred of wickedness remain constant forever.