yummyfur

Actually it doesn't seem to be the images, but the purity of the silver content. The most popular coins for the Temple tax were the shekels minted in Tyre, because their silver content was not debased as in other coins, though they had images of pagan gods(Melqart).

There was definately a feeling in the first century, that sacrificial animals were seriously overcharged for, especially the common doves and turtle doves which were used by the poorer folks. These had to be blemish free to be sacrifised, so one could not neccasarily bring your own. In Matthew and Mark it is the moneychangers and those selling doves who are accosted. They do not mention other animal vendors, though John does.

Amaleq13

I think you may be correct that the purity of the Tyrian silver was of paramount importance but the coins for Temple use were apparently minted in Jerusalem, using Tyrian silver, rather than in Tyre. But I've also read that the images on foreign coins was a problem though it is sometimes specified that only human images were forbidden (ie of emperors). Why an image of Melqart would be allowable, I don't understand.

yummyfur

The ones minted in Jerusalem looked exactly the same, except they were of cruder workmanship. They were meant to be copies, and were started by Herod the Great, probably because the Romans had started to debase the silver content of the true Tyrian shekel. Though there is debate on wether these coins are actually minted in Jerusalem.

This has always been a puzzle to me as well, why mint them to look the same, was it such a long tradition, that the image became synonymous with a guarantee of purity and the Temple tax? This doesn't seem likely as they have only been around since about 126 BC. Is it the connection of Hiram of Tyre in helping to build the Solomonic Temple?

Amaleq13

And, after c.70CE, they changed the images on both sides of the coins to feature Jewish symbols, right?

yummyfur

After 65 the seditious minted their own coins with Jewish symbols, this lasted til 70 CE. Technically I think the true Tyrian shekels were no longer minted after 57 CE anyways, and even these were rare. What's strange, is that the Romans minted coins with only Jewish symbols, during most of their control before the revolt, why would the shekels be different?

Another thought I had, the Tyrian shekels were autonomous productions satrting in 126 BC, which replaced the image of the Seleucid Kings on the Tetradrachm with Melquart. Maybe the Jews preferred both the shekel denomination and not having the Seleucid image, as well as the fine quality of the coins. This might have been the original motivation to use the coins, despite the Melquart image(Melquart's better than Seleucid), and then it became tradition.

Anyways the purity of the silver is important, and could have caused significant unrest about the Temple tax. If there was inflationary conditions and generalized debasement of most currency in use, which I beleive there was. The requirement of using a certain weight of silver, would have made the Temple tax increasingly expensive for the population. Also I beleive that since Augustus's reign, the Romans allowed the Temple tax to be collected from Diaspora Jews, this might have made some people unhappy, and could have created strange currency issues.

An additional thought, is that the Jerusalem Tyrian Shekels started being produced around 18 BC. In 20 BC Herod started his Temple project, and I believe received permission from Augustus, who then approved the Temple tax collection on Diaspora Jews, probably to help with building the new Temple. It's possible that Herod's need for more Tyrian shekels of good silver value to support his expensive Temple work and the new ability to collect the tax from the rest of the Roman empire, required him to mint his own, as Tyre's production had declined with political changes.