"The earliest known examples of Mithras worship date back 4000 years to the Persian empires"
Judaism absorbed aspects of Zoroastianism/Mithras, so the old testament writings do not predate the Mithras mysteries quite so easily. (Judaism actually took on many of the Zoroastrian/Mithras ideas during the Babylonian captivity)
Nice try though.
I will give you that there was the possibility of cross talk between ancient Judaism and Mithras and 'who influenced who' will certainly always be up for debate.
However, the fact remains that the Mithras pagan mystery cult mirrors (and certainly pre-dates) Christianity. It even predates Judaism. And it was very popular. In fact, as one writer put it, if not for Constantine, we would probably all be worshipping Mithras today....