All Scripture quotes are from the TNIV unless otherwise noted.
First, Jesus’ words to the dove-sellers in v16 are noteworthy for figuring out what’s going on here: “Stop turning my Father’s house into a market!”
To point out the obvious, Jesus draws a clear contrast between the Temple and the marketplace. I think this is saying more about the purpose of the Temple than about the persons selling livestock and exchanging money. They were, after all, performing a service that assisting the Temple in being the Temple for folks. Some persons needed an appropriate sacrifice to bring to the Temple in order to worship properly. Some (many?) of those folks were poor and needed the service that the sellers provided. Also, persons whose local currency did not match what was used in the Temple would have appreciated the money-changers’ service, helping them exchange their currency for one that was useful in the Temple.
Nonetheless, Jesus’ “zeal for [God’s] house” has consumed him (as the disciples remember later). Jesus’ words in v16 allude to Zechariah 14:20-21, especially the last phrase of those verses (and the book): “And on that day there will no longer be a merchant in the house of the Lord Almighty” (though the TNIV says “Canaanite” instead of “merchant,” merchant seems to be the better reading, and one that is shared by the NRSV and The Message). Zechariah was a prophet in Israel who led the people in rebuilding the Temple. He emphasized purity and devotion to God, marking everything as “Holy to the Lord,” in other words, ‘”fully devoted to God.”
In the context of Zechariah, we can see the continued significance of Jesus’ response to the request for a sign. Jesus seems to continue his imaginative drawing upon Jewish history: Destroy this temple, and I will raise it up again in three days. Perhaps the point is related to what Zechariah was saying: when the Temple is rebuilt, it will be truly “Holy to God” or “fully devoted to God” because the person of Jesus is the new Temple.
The Temple was the place where persons could encounter the presense of God, where heaven and earth touch or overlap, to use NT Wright’s way of talking about it. God is everywhere, but God is present in the Temple in a uniquely powerful way, unlike anywhere else (see Solomon’s prayer of dedication in 1 Kings 8 and 2 Chronicles 6, esp. vv40-42). So, here, as Jesus cleanses the Temple, his answer in v19 seems to suggest that he himself is the Temple’s replacement as well.