So Peter was persecuting the 3000 that were lost (but thought they were right with God) Per Acts 2(38)?
Peter preached a message of salvation through Jesus Christ. He had the anointing of the Holy Spirit upon him and when He preached the Word signs and wonders followed. Peter ministered the love of Jesus and offered hope to those who feared God.
Peter preached with a humble spirit and did not place condemnation on anyone.
Acts 2 (KJV)
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³³ Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear.
³⁴ For David is not ascended into the heavens: but he saith himself, The LORD said unto my Lord, Sit thou on my right hand,
³⁵ Until I make thy foes thy footstool.
³⁶ Therefore let all the house of Israel know assuredly, that God hath made that same Jesus, whom ye have crucified, both Lord and Christ.
³⁷ Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?
³⁸ Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
³⁹ For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.
⁴⁰ And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation.
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Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.
⁴² And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers.
Nowhere, absolutely NOWHERE, in the Bible does it say anything about getting saved the right way....as if to suggest that a person can err in confessing with their mouth and believe in there heart that Jesus is the only begotten Son of God who came and became a sacrifice for their sins.
And if anyone who confesses and repents of their sins and calls upon Him they shall be saved.