Does Acts 2:38 tell us we need baptism to be saved?

Someone recently asked this question, and a quick reading of the text certainly indicates this:

Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, “Brothers, what shall we do?” 

And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit.” (Acts 2:37–38)

However, we must be careful students of God's Word.  Is this what the text is really saying?  So, let's go on a journey into the Greek:

Πέτρος δὲ πρὸς αὐτούς· 

μετανοήσατε, [φησίν,] 

καὶ βαπτισθήτω ἕκαστος ὑμῶν ἐπὶ τῷ ὀνόματι Ἰησοῦ Χριστοῦ εἰς ἄφεσιν τῶν ἁμαρτιῶν ὑμῶν 

καὶ λήμψεσθε τὴν δωρεὰν τοῦ ἁγίου πνεύματος. 

• First, note the shift in the language:
• in the first part of the verse, Peter addresses them corporately (“y’all repent”); 
• in the second part of the verse, he addresses them singularly (“and be baptized every one of you”) 
• then switching back to the plural (“for the forgiveness of sins y’all have”).   
• More importantly, though, note the meaning of “for”: 
• the accusative preposition eis means “as the result of,” not “the purpose of,” though other constructions would allow this meaning of eis.  
• The construction in Acts 2:38 is the same as is used in Matthew 10:41—“The one who receives a prophet eis onoma prophētou (“in the name of a prophet” or “because of a prophet’s name”) will receive a prophet’s reward.”
• There is no punctuation in the original Greek.  When we read a critical Greek text, like the UBS NA27 I quoted above, the punctuation is supplied as a guide like Bible verses are, and should not be considered inspired.
• If it is an imperative (command), you can have a one-word sentence in English.
• As such, the verse could be translated thusly:

Repent. And let each one of you be baptized in the name of Jesus Christ in that forgiveness of sins you all have, and you all will receive the gift of the Holy Spirit. 

As you can see, the verse presents baptism as a sign of one joining the community of the forgiven, not a step to gain entrance.  

That's good.  We might have had a conflict with other Scripture, which is clear that salvation is “not of works” (Eph 2:8-9).  Close one.