Eis
It is sometimes affirmed that 'eis' (FOR the remission of sins) means BECAUSE of and not IN ORDER TO. That 'for' in the English sometimes is used this way is not to be denied - i.e., He was sent to prison for stealing. However, does the greek word mean this? Why would we understand it to mean that in this passage?
The customary meaning is 'for, in order to, with a view to'. The word is found 1176 times being translated in KJV as 'to, unto, into, or towards'. Another 559 it is translated with other words. It is NEVER translated "because of' or 'in reference to'.
The only other time it is found in the phrase 'for the remission of sins' is in Matthew 26:28 - "this is my blood which is shed for the remission of sins'. Here the normal meaning of the word is seen - and it assuredly does NOT mean 'because of' but rather 'unto, into, or towards'.
The only reason it is suggested that EIS in Acts 2:38 is to have a 'special' meaning is because of predisposed theological conclusions - i.e., 'it cannot mean 'in order to' because then baptism would be necessary for the remission of sins.'
I would suggest that that is the very meaning of this passage.