Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and peace, be multiplied.
Foreknowledge - foreordaining love (1 Peter 1:20) inseparable from God's foreknowledge, the origin from which, and pattern according to which, election takes place. Acts 2:23, and Romans 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' (Greek for "foreordained," 1 Peter 1:20) to be the sacrificial Lamb; not without His will, but His will resting in the will of the Father. This includes self-conscious action-nay, even cheerful acquiescence. The Scriptural "know" includes approval and acknowledging as one's own. The Hebrew marks the oneness of loving and choosing by having one word for both х baachar (H977)] [Septuagint, hairetizoo]. Peter descends from God's eternal 'election,' through the new birth, to believers' "sanctification," that from this he may again raise them through 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. 'Election' realizes itself 'IN' their sanctification. Believers are "sanctified through the offering of Christ once for all" (Hebrews 10:10). 'Thou must believe that thou art holy; not, however, through thine own piety, but through the blood of Christ' (Luther). The true sanctification of the Spirit is to obey the Gospel, to trust in Christ (Bullinger).
Sanctification - the Spirit's setting apart of the saint as consecrated to God. The execution of God's choice (Galatians 1:4). God the Father gives us salvation by gratuitous election: the Son earns it by His bloodshedding: the Holy Spirit applies the Son's merits to the soul by the Gospel word (Calvin). Compare Numbers 6:24-26, the Old Testament triune blessing.
Unto obedience - the end aimed at by God as respects us, the obedience which consists in, and that which flows from, faith: "obeying the truth through the Spirit" (1 Peter 1:22; Romans 1:5).
Sprinkling ... Not justification through the atonement once for all, which is expressed in the previous clauses, but (as the order proves) the daily sprinkling by Christ's blood, cleansing from all sin, which is the privilege of one already justified and "walking in the light" (1 John 1:7; John 13:10).
Grace - the source of "peace."
Be multiplied - (Daniel 4:1.) 'Ye have peace and grace, but still not in perfection: ye must go on increasing until the old Adam be dead' (Luther).