The following English Bible translations varied in how they render the phrase ἐν ἁγιασμῷ πνεύματος.
''in the sanctification of the Spirit'' (ESV)
''by the sanctifying work of the Spirit'' (NASB)
''His Spirit has made you holy'' (NLT)
I think that the ESV reading is the most literal. However, I doubt that it's the case. I did some research and I found out that the the Greek preposition ἐν in this verse is in the instrumental dative.
How can we accurately translate the Greek phrase ἐν ἁγιασμῷ πνεύματος into English?