That salvation is according to the everlasting covenant of grace and that paul and the apostles preached it so is seen in phrases as the " counsel of God" Acts 20:27
27For I have not shunned to declare unto you
all the counsel of God.The word counsel is the word boulē:
counsel, purpose
The Purpose of God He did not shun to declare ! Peter preached it here Acts 4:28
28For to do whatsoever thy hand and
thy counsel determined before to be done.[I believe this counsel refers to the everlasting covenant determined in the GodHead]
Now this [Acts 20:27] was when paul was addressing the Ephesian elders Acts 20:17,24
17And from Miletus
he sent to Ephesus, and called the elders of the church.
and He was speaking about the Gospel of God's Grace vs 24
24But none of these things move me, neither count I my life dear unto myself, so that I might finish my course with joy, and the ministry, which I have received of the Lord Jesus,
to testify the gospel of the grace of God.So this leads us to believe that paul was rehearsing the first chapter of Ephesians as part of God,s Gospel of Grace Eph 1:6,11
6To the praise of the glory of his grace, wherein he hath made us accepted in the beloved.
11In whom also we have obtained an inheritance, being predestinated according to the purpose of him who worketh all things after
the counsel of his own will
The word counsel here is the same word as used in Acts 20:27 and Acts 4:28
Also Paul spake of the wisdom of God 1 Cor 2:6
6Howbeit
we speak wisdom among them that are perfect: yet not the wisdom of this world, nor of the princes of this world, that come to nought:
That word wisdom is the greek word Sophia and one of its meanings is:
supreme intelligence, such as belongs to God
1) to Christ
2) the wisdom of God as evinced
in forming and executing counsels in the formation and government of the world and the scriptures see Eph 3:10
And that would be that wisdom that contrived the everlasting covenant, whereby God was in Christ reconciling the world unto Himself, through the surety engagement with Christ for His People, not imputing their trespasses on them, because they were imputed to the Surety of the Covenant 2 Cor 5:21, so He would in due time come and be a sin offering in their behalf Isa 53:10
10Yet it pleased the LORD to bruise him;
he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the LORD shall prosper in his hand.
Christ was long the designated sin offering before the world began ! The world was created within the scope of that purpose Eph 3:9
9And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God,
who created all things by Jesus Christ:please cp Eph 3:9 with 2 Cor 5:19 in regards to the preposition in !