My covenant will I not break, nor alter the thing that is gone out of my lips.
Read Chapter 89
Augustine of Hippo
31. "My covenant will I not profane, nor reject the thing that is gone out of my lips" (ver. 34). Because his sons sin, I will not on this account be found false: I have promised; I will do. Suppose they choose to sin even as past hope, and so fall into sins as to offend their Father's countenance, and deserve to be disinherited; is it not still God Himself, of whom it is said, "From these stones" He "will raise up sons to Abraham"? Therefore I tell you, brethren, many Christians sin venially, many are scourged and so corrected for their sin, chastened, and cured; many turn away altogether, striving with a stiff neck against the discipline of the Father, even wholly refusing God as their Father, though they have the mark of Christ, and so fall into such sins, that it can only be announced against them, "that they who do such things shall not inherit the kingdom of God." Nevertheless, Christ shall not be destitute of an inheritance on their account: not for the chaff's sake shall the wheat also perish: nor on account of bad fish shall nothing be cast into the vessels from that net. "The Lord knows them that are His." For He who predestined us before we were born, promised undoubtingly: "For whom He did predestinate, them. He also called: and whom He called, them He also justified: and whom He justified, them He also glorified." Let desperate sinners sin as far as they choose: let the members of Christ reply, "If God is with us, who shall be against us?" God will not therefore do hurt in His truth, nor will He "profane His Testament." His Testament remains immovable, because in His foreknowledge He predestined His heirs; and "He will not reject the thing that is gone out of His lips."