1 Corinthians 15:3

For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;

I delivered unto you. A short summary of articles of faith was probably even then existing (cf. Ephesians 4:4; Hebrews 6:1, etc.; 1 John 4:2); and a profession of it was required of candidates for baptism, (Acts 8:37; Romans 10:9).

First of all - literally, 'among the foremost points' (Hebrews 6:2). The atonement is, in Paul's view, of primary importance.

Which I also received - from Christ by special revelation (cf. 1 Corinthians 11:23). Paul "delivered" what he "received;" not something of his own origination.

Died for our sins - i:e., to atone FOR them, for taking away our sins (1 John 3:5). ["For" is here huper (G5228), 'in behalf of' So Galatians 1:4; 2 Corinthians 5:15; Titus 2:14: cf. Isaiah 53:5; 1 Peter 2:24; Hebrews 5:3 has dia (G1223), implying that the object is the center round which the action concentrates. Romans 4:25 has anti (G473), 'on account of.' In Matthew 20:28 anti (G473), instead of, implying substitution, or vicarious satisfaction (cf. Greek, Matthew 17:27; Luke 11:11; 1 Corinthians 11:15).]

According to the Scriptures - which 'cannot be broken.' To deny the resurrection is to renounce the prophetic Scriptures, which it fulfills (Hosea 6:2). Paul puts their testimony before that of the witnesses to Christ's resurrection. So Christ quotes Isaiah 53:12 in Luke 22:37 (cf. Psalms 22:15. etc.; Daniel 9:26).