Joshua, the difference between Ares and Mars is striking. (Indeed, most Roman legionaires would frown on a soldier who acted like Ares.) Also, while I did not know about the incident concerning Julius Caesar, I am not surprised. The Romans seemed to portray themselves as superior to the Greeks morally and in terms of military might. I suppose a love-hate relationship is not too surprising.
The Romans were well known for conquering an area and then doing a very good job assimilating the population. They did this in a few key ways, one of which was basically "god swapping".
Let's say the Romans take over your country, CRG-land.
Roman: "Hey check you out - you worship CRG, like all good people do."
Local: "What? You've heard of CRG? I thought you were a heathen!"
Roman: "Hell no! CRG is just another name for Janus. Check this out, CRG is all kinds of (describe similarities, discussion ensues). We've got no problems with you continuing to worship CRG."
Local: "Really?"
Roman: "Sure, as long as you remember that we're the army here and we destroyed your temple to CRG when we moved in. That said, we're also the government now and will be building a new temple as part of the imperial cult. You'll keep going there, just like you did for CRG right? I mean, you want us to like you, right? You want to worship our...er...I mean your god, don't you?"
(Temple is built, has a mix of inconography showing Janus and CRG images, etc. This and other assimiliation projects ensure that various other differences are smoothed out. Time passes, Janus and CRG are now functionally equated.)
They did a number of other things to ensure loyalty and the like. Another favorite was when people volunteered / were conscripted into legionary service they were, as a rule, never stationed near their homes. Instead, you find Assyrians in the garrisons in Spain, etc.
When its all said and done, you've been Romanized.