What is the core of Paul's Gospel about Christ's death?
The core is that Christ died for our sins on the cross according to the Scriptures. Paul delivered this first of all as what he also received; it was no accident, but God's preplanned redemption, already in His foreknowledge and counsel, as Peter confirms in Acts chapter 2.
Les explains that this is the Gospel Paul preached: Christ died for our sins when He hung on the cross according to the Scriptures. Paul delivered first of all what he also received, and it was not an accident. God had already planned it in the eons of pre-eternal existence: He would create mankind, man would sin, and He would bring about a plan of redemption. This was all in the foreknowledge and counsel of God, according to Peter in Acts chapter 2. Les stresses that this Gospel saves and prepares believers for eternity, and while John 3:16 is valid, it does not contain this part of the Gospel; it must be used in conjunction with it. Believers are saved, but they must know what they believe.
For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;