It should be a truism that knowing Greek (or at least being familiar with it) is useful for preachers. I would go further and say that it is necessary for a long term ministry because knowing the Scripture in the original gives allows the preacher to explain the Bible not only in terms of his or her experience of obeying Jesus, but by genuine descriptive knowledge of its contents. Both kinds of knowledge are important.
Case in point:
NAS 27 Romans 3:25 ὃν προέθετο ὁ θεὸς ἱλαστήριον διὰ [τῆς] πίστεως ἐν τῷ αὐτοῦ αἵματι εἰς ἔνδειξιν τῆς δικαιοσύνης αὐτοῦ διὰ τὴν πάρεσιν τῶν προγεγονότων ἁμαρτημάτων
NET Romans 3:25 God publicly displayed him at his death as the mercy seat accessible through faith. This was to demonstrate his righteousness, because God in his forbearance had passed over the sins previously committed.
NRS Romans 3:25 whom God put forward as a sacrifice of atonement by his blood, effective through faith. He did this to show his righteousness, because in his divine forbearance he had passed over the sins previously committed;
ASV Romans 3:25 whom God set forth to be a propitiation, through faith, in his blood, to show his righteousness because of the passing over of the sins done aforetime, in the forbearance of God;
Note the bold text. These are related, but nevertheless different notions expressed by three English words. All of them translate one Greek word (ιλαστηριον). It certainly is true that Jesus’ death was a sacrifice (Ephesians 5:1) and it is true that Jesus’ death propitiates/atones for/expiates God’s wrath in some way related to priestly sacrifices (Hebrews 9).
But, these are not the direct import of Romans 3:25. The referent for the Greek word there is pretty clearly the mercy seat. For instance Daniel Bailey looks to Philo, Jewish Apocalyptic Literature and to the LXX (Exodus, Leviticus, Numbers, and IV Maccabees) to find help:
Applying the biblical sense of ἱλαστήριον to Jesus in this theologically pregnant way would not have been entirely unprecedented for Paul, since Philo thought of the mercy seat as σύμβολον τῆς ἵλεω τοῦ θεοῦ δυνάμεως, ‘a symbol of the gracious power of God’ (Mos. 2.96; cf. Fug. 100). Perhaps this shows that Philo traced the term ἱλαστήριον etymologically not to ἱλάσκεσθαι (‘to propitiate or expiate’) but to ἵλεως, ‘gracious’ or ‘merciful’. This would then support the translation by ‘mercy seat’, though the vaguer expression ‘place of atonement’ is also in common use (NRSV mg. at Rom. 3:25 and Heb. 9:5). The old objection that Paul cannot have alluded to ‘the’ well-known ἱλαστήριον of the Pentateuch without using the Greek definite article is baseless, since Philo clearly uses anarthrous ἱλαστήριον to refer to the mercy seat (Mos. 2.95, 97; Fug. 100).
158 TYNDALE BULLETIN 51.1 (2000)
In other words, at this juncture Paul is making the point, not that Jesus is the atonement, but rather that he is the place of atonement and revelation. The mercy seat in Exodus was both a place of where sacrificial offerings were made, but it stood as a symbol for God’s kindness revealed to the Israelites. This is very important because Paul is arguing that Jews and Gentiles who come to Jesus are justified in the same way (because they are both sinful) and need not judge or places extra strictures upon one another (even ones from the OT law). Jesus is the place where they are both made right with God. Not simply a sacrifice that different kinds of people have access to, but a metaphorical sacrificial site. To him must different kinds of people come together to be declared righteous by God. But they must come together to him or they have not yet come. Not only so, but his cross represents and reveals God’s mercy to us in that it is God’s mercy to us.
This is in keeping with Romans 1:16-18: the gospel reveals God’s righteousness. In the story of Jesus, crucified, buried, risen, and reigning, the hopes of the ancient Israelites were fulfilled, including the promise to be a blessing to the whole world.