“When you are offering
Your gift
At the altar,
If you remember
That your brother
Has something
Against you,
Leave your gift there
Before the altar!
Go away!
First be reconciled
To your brother!
Then come!
Offer your gift!”
ἐὰν οὖν προσφέρῃς τὸ δῶρόν σου ἐπὶ τὸ θυσιαστήριον κἀκεῖ μνησθῇς ὅτι ὁ ἀδελφός σου ἔχει τι κατὰ σοῦ
ἄφες ἐκεῖ τὸ δῶρόν σου ἔμπροσθεν τοῦ θυσιαστηρίου καὶ ὕπαγε πρῶτον διαλλάγηθι τῷ ἀδελφῷ σου, καὶ τότε ἐλθὼν πρόσφερε τὸ δῶρόν σου.
Matthew alone continued to point out to these Jewish listeners that they should reconcile with their brothers or sisters, before they presented their gift offerings at the Temple. This would seem to indicate that the followers of Jesus were still offering sacrifices at the Jerusalem Temple. This also would assume that the Temple was still standing. Very clearly, these followers of Jesus, or early Christians, were offering their gifts at the altar (ἐὰν οὖν προσφέρῃς τὸ δῶρόν σου ἐπὶ τὸ θυσιαστήριον). If they remembered that their brother had something against them (κἀκεῖ μνησθῇς ὅτι ὁ ἀδελφός σου ἔχει τι κατὰ σοῦ), they should leave their gift offerings there (ἄφες ἐκεῖ τὸ δῶρόν σου ἔμπροσθεν τοῦ θυσιαστηρίου). Then they should go and be first reconciled with their brother (καὶ ὕπαγε πρῶτον διαλλάγηθι τῷ ἀδελφῷ σου), which was a common Jewish custom. Then they could come back to the Temple and offer their gifts. All’s well that ends well. There was no reconciliation with God without being reconciled with your brother first.
Eugene Finnegan Bible Project 