"Is it not possible that taxation of churches could grant those with a large parish, public activities, or considerable properties/assets more influence in government policies?"
Hardly. Influence is based on donations and other favors to political parties, and politicians in power, not on account that taxes are payed.
Members of a church can already do this through indirect means.
As far as "leveling the playing field", that concept is an ideal not based on reality, but on the false presumption that equal access or opportunity means equality of outcome. Life does not provide a level playing field for anything, and does not guarantee outcomes. Satanists recognize that life is survival of the fittest, and leverage their actions to influence outcomes in order to benefit them as best they can.
There is another forum where politics are discussed, so your question will not be debated in depth here.
"Consensus is the absence of leadership." Margaret Thatcher
"I'm fascinated with how primitive the human mind still is. It can be misdirected so easily." John Gaughan
"Success is uncommon. Therefore, not to be enjoyed by the common man." Cal Stoll