Under Covenant, Peter told Israel that if they would repent (change their mind) their sins would get blotted out in the future. When they're back in "the presence of the Lord" is when He will blot out the sins of those who "endureth to the end". (Matthew 10:22)
Acts 3:19 Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord
Under Grace, Paul writes that according to the "dispensation of the gospel" that was committed to him, (1 Corinthians 9:17) Christ death was for "ALL trespasses" therefore we already HAVE forgiveness.
Colossians 2:13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
Ephesians 1:7 In whom we have redemption through his blood, the forgiveness of sins, according to the riches of his grace;
"having forgiven;" means it's already taken place.
"we have...forgiveness of sins," means we are not waiting to be in the presence of the Lord before we GET it.
It is obvious that Peter taught FUTURE forgiveness for Israel, which differs from Paul's teaching of PRESENT forgiveness for us.
Regardless of what Twistianity continues to teach, Peter and Paul did NOT teach the same thing about forgiveness of sin.
"Truth is the only safe ground to stand on."