μετανοεῖτε · ἤγγικεν γὰρ ἡ βασιλεία τῶν οὐρανῶν.
Consider the grammar of salvation in Matthew 4:17.
- Repent – μετανοειτε – present, imperative of μετανοέω
- Has come near – ηγγικεν – perfect, indicative of ἐγγίζω
The second part of the sentence logically precedes the first part. Something has happened that has ongoing results – or created a new state of being – in the world. Therefore, you should be doing something.
What has happened?
- The kingdom of heaven (or kingdom from heaven) has drawn near.
What should you be doing?
- You should be repenting. The active imperative connotes an ongoing action.
Matthew spends the rest of his gospel showing us the kingdom’s drawing near and what it means to repent.