Acts 3:
17 “And now, brethren, I know that you acted in ignorance, just as your rulers did also. 18 But the things which God announced beforehand by the mouth of all the prophets, that His Christ would suffer, He has thus fulfilled. 19 Therefore repent and return, so that your sins may be wiped away, in order that times of refreshing may come from the presence of the Lord; 20 and that He may send Jesus, the Christ appointed for you, 21 whom heaven must receive until the period of restoration of all things about which God spoke by the mouth of His holy prophets from ancient time.
"Him, being delivered by the determinate counsel and foreknowledge of God, ye have taken, AND BY WICKED HANDS HAVE CRUCIFIED AND SLAIN:" Acts2:23. Does THIS sound like good news? Does this sound like he is preaching the cross as good news and their salvation?
Well yes it is the good news. It is the brutal truth. Messiah had to suffer and die for sinners. Peter speaks truth here. We are all wicked and only the death and resurrection of Jesus Christ releases us from the bonds of Satan. Peter was giving the very people who yelled "crucify him, crucify him" weeks earlier the gospel of Grace right between the eyes. And some "were cut to the heart."
If you don't believe me, let's look at what Jesus Christ said was the good news:
Luke 24:
44 Then He said to them,“These are the words which I spoke to you while I was still with you, that all things must be fulfilled which were written in the Law of Moses and the Prophets and the Psalms concerning Me.” 45 And He opened their understanding, that they might comprehend the Scriptures. 46 Then He said to them, “Thus it is written, and thus it was necessary for the Christ to suffer and to rise from the dead the third day, 47 and that repentance and remission of sins should be preached in His name to all nations, beginning at Jerusalem. 48 And you are witnesses of these things. 49 Behold, I send the Promise of My Father upon you; but tarry in the city of Jerusalem until you are endued with power from on high.”
Now, with the Words of Christ presented, let's move to 1 Corinthians 15 once again to see what Paul said was the Gospel:
1 Corinthians 15:
15 Moreover, brethren, I declare to you the gospel which I preached to you, which also you received and in which you stand, 2 by which also you are saved, if you hold fast that word which I preached to you—unless you believed in vain.
3 For I delivered to you first of all that which I also received: that Christ died for our sins according to the Scriptures, 4 and that He was buried, and that He rose again the third day according to the Scriptures, 5 and that He was seen by Cephas, then by the twelve. 6 After that He was seen by over five hundred brethren at once, of whom the greater part remain to the present, but some have fallen asleep. 7 After that He was seen by James, then by all the apostles. 8 Then last of all He was seen by me also, as by one born out of due time.
9 For I am the least of the apostles, who am not worthy to be called an apostle, because I persecuted the church of God. 10 But by the grace of God I am what I am, and His grace toward me was not in vain; but I labored more abundantly than they all, yet not I, but the grace of God which was with me. 11 Therefore, whether it was I or they, so we preach and so you believed.
Now Peter in Acts chapter 3:
Acts 3:
17 “Yet now, brethren, I know that you did it in ignorance, as did also your rulers. 18 But those things which God foretold by the mouth of all His prophets, that the Christ would suffer, He has thus fulfilled. 19 Repent therefore and be converted, that your sins may be blotted out, so that times of refreshing may come from the presence of the Lord, 20 and that He may send Jesus Christ, who was preached to you before, 21 whom heaven must receive until the times of restoration of all things, which God has spoken by the mouth of all His holy prophets since the world began.
Jesus Christ, Peter and Paul preached the same Gospel. The death and resurrection and future return of Jesus Christ IS the Gospel of Grace. Without Christ's death and resurrection, there is no remission of sins. All three passages match.
I don’t think your Acts 3 passage works for you like you would think. Peter wasn’t telling them the Jesus died for their sins. He told them He suffered just as their prophets had told them and that they needed to change that their sins may be forgiven just as they had been told throughout the Old Testament. And then look at verse 20 “and that he may send the Messiah, who has been appointed for you—even Jesus”. That he may “send the Messiah”? Peter was still talking about Jesus coming back as King and ruler in Israel.
Nah...Peter knew nothing of the gospel of the grace of God...Peter knew nothing of the Gentile church....
Peter was preaching the gospel of the kingdom of Heaven...To Jews...He was preaching the 'restoration of all things', not the formation of the church as we know it...
Peter and the apostles were under the law...They were looking for their Messiah to return from heaven to set up and physically rule his Kingdom in Jerusalem, without any knowledge of a gentile church...
There is no salvation by grace thru faith in Peter's/Jesus' gospel...That wasn't revealed to anyone til after the Jews rejected their Messiah and the promise was given to the Gentiles...
Peter was preaching a physical kingdom...Paul taught a spiritual kingdom...
Jesus taught that if you repent and are baptized (in water) you would have a place in this physical kingdom...