1 John 4:7

ὁ μὴ ἀγαπῶν οὐκ ἔγνω τὸν θεόν, ὅτι ὁ θεὸς ἀγάπη ἐστίν

The one who does not love does not know God because God is love


 * μὴ ἀγαπῶν - present active participle masculine sg. nominative
 * οὐκ ἔγνω - "knew not" is in the aorist. 2nd aorist active indicative 3 sg. It does not imply past time:
 * could be implying a timeless fact, looking at the action as a whole event, with perfective aspect. So could be translated as "doesn't know".
 * or could be ingressive aorist - focussing on the inception or beginning of the action i.e. never came to know God. Never started to know God. We are looking at a person e.g. purported a Christian but who is not loving. We diagnose why and infer by looking into his past and postulate that he never came to know God.
 * ὁ θεὸς ἀγάπη ἐστίν - θεὸς is the subject as indicated by the article. ἀγάπη is the predicate nominative. ἐστίν is the linking verb. Note ἐστίν is not an equal sign. It is not reversible. God is love, but love is not God.