The best way to understand the phrase in
Acts 2:38 is to see how it is used in other passages:
In
Acts 2:38, the Greek phrase:
eis aphesin ton hamartion
We can compare this to
Matthew 26:28:
eis aphesin hamartion
Mark 1:4:
eis aphesin hamartion
Luke 1:77:
aphesei hamartion
Luke 3:3:
eis aphesin hamartion
Luke 24:47:
eis aphesin hamartion
Acts 5:31:
kai aphesin hamartion
Acts 10:43:
aphesin hamartion
Acts 13:38:
aphesin hamartion
Acts 26:18:
autous aphesin hamartion
Colossians 1:14:
ten aphesin ton hamartion
Of key importance is the way the author of Luke-Acts uses the phrase, since such a use will likely be similar in scope and meaning, sic passim.