1 Peter 1:2

foreknowledge--foreordaining love (Pe1 1:20), inseparable from God's foreknowledge, the origin from which, and pattern according to which, election takes place. Act 2:23, and Rom 11:2, prove "foreknowledge" to be foreordination. God's foreknowledge is not the perception of any ground of action out of Himself; still in it liberty is comprehended, and all absolute constraint debarred [ANSELM in STEIGER]. For so the Son of God was "foreknown" (so the Greek for "foreordained," Pe1 1:20) to be the sacrificial Lamb, not against, or without His will, but His will rested in the will of the Father; this includes self-conscious action; nay, even cheerful acquiescense. The Hebrew and Greek "know" include approval and acknowledging as one's own. The Hebrew marks the oneness of loving and choosing, by having one word for both, bachar (Greek, "hairetizo," Septuagint). Peter descends from the eternal "election" of God through the new birth, to the believer's "sanctification," that from this he might again raise them through the consideration of their new birth to a "living hope" of the heavenly "inheritance" [HEIDEGGER]. The divine three are introduced in their respective functions in redemption. through--Greek, "in"; the element in which we are elected. The "election" of God realized and manifested itself "IN" their sanctification. Believers are "sanctified through the offering of Christ once for all" (Heb 10:10). "Thou must believe and know that thou art holy; not, however, through thine own piety, but through the blood of Christ" [LUTHER].

— Jamieson-Fausset-Brown Commentary (public domain)