If ye know that he is righteous, ye know that every one that doeth righteousness is born of him.
If you know that he is righteous, you know that everyone who does what is right has been born of him.
Ἐὰν εἰδῆτε ὅτι δίκαιός ἐστιν, γινώσκετε ὅτι πᾶς ὁ ποιῶν τὴν δικαιοσύνην ἐξ αὐτοῦ γεγέννηται.
Ean eidēte oti dikaios estin, ginōskete oti pas o poiōn tēn dikaiosynēn ex aytoy gegennētai.