Who hath saved us, and called us with an holy calling, not according to our works, but according to his own purpose and grace, which was given us in Christ Jesus before the world began,
Who ... called us - namely, God the Father (Galatians 1:6). The "saved us" in His purpose of "grace, given us in Christ before the world began," precedes His "calling" us in due time with a call made effective by the Holy Spirit; therefore, "saved us" comes before "called us" (Romans 8:28-30).
Holy calling - the actual call to holiness, and "the fellowship of His Son" (1 Corinthians 1:9; Hebrews 3:1, "heavenly calling:" whereas we were sinners and enemies, Ephesians 1:18; Ephesians 4:1). The call comes wholly from, and claims us wholly for, God. "Holy" implies the believer's separation from the world unto God.
Not according to - not having regard to our works in His election and calling (Romans 9:11; Ephesians 2:8-9).
His own purpose. Salvation originated from His own purpose of goodness; not for works of ours, but wholly of His gratuitous, electing love (Theodoret and Calvin).
Grace which was given us - in His everlasting purpose, regarded as actually given.
In Christ. Believers are viewed by God as IN HIM, with whom the Father makes the covenant (Ephesians 1:4; Ephesians 3:11).
Before the world began, х pro (G4253) chronon (G5550) aioonion (G166)] - 'before eternal times:' before times marked by the lapse of unnumbered ages (Ellicott). From eternity [Aionios]. 'That of which no end is conceived' (Tittmann) (1 Corinthians 2:7; Ephesians 3:11).