Polytheism,

In my opinion, the biggest factor in the decline of polytheism was the influence of political power exerted by those who conquered or in some way took control of an area that contained people who had polytheistic beliefs.

In the Bronze Age, polytheism was practiced in different forms by smaller communities scattered around an area. It was difficult to keep track of multiple gods and goddesses and to give them equal attention. Time constrained the number of ritual practices that could be performed in a day for every god/goddess in the pantheon, so each community would favour their own god/s and goddess/es. With no two communities evolving to have identical beliefs, the individual communities were poorer in terms of faith identity in comparison to the larger monotheistic religions, so they were easily swept into the religion of those who wielded control. 

In the case of Mesopotamia, multiple conquests meant gods and goddesses were assimilated into those of the conquering communities. Over time, elements of these gods/goddesses could be seen in the polytheistic practices of communities scattered across what is now the Levant, ending up in early Judaism. The Hebrew Bible gives numerous examples and hints of what has been before, and the brilliant thing is there is also evidence of its polytheistic ancestry from historical and archaeological sources. 

The polytheistic religion of Ancient Greece inherited elements of Mesopotamian polytheism, eventually being overtaken by Christianity. The conversion of Constantine to Christianity and the expansion of the Roman Empire made Christianity an attractive alternative for many, for others the religion was forced upon them. 

The early Muslim conquests beginning in the 7th century were responsible for the spread of Islam, with the empire expanding rapidly from Arabia into North Africa and southern Europe. As was elsewhere with the rise of Judaism and Christianity, remaining polytheistic communities would have have had difficulty surviving.

I imagine you would find your polytheistic beliefs easier to maintain than it would have been for many pagans and others years ago. 

In my opinion, the biggest factor in the decline of polytheism was the influence of political power exerted by those who conquered or in some way took control of an area that contained people who had polytheistic beliefs.

In the Bronze Age, polytheism was practiced in different forms by smaller communities scattered around an area. It was difficult to keep track of multiple gods and goddesses and to give them equal attention. Time constrained the number of ritual practices that could be performed in a day for every god/goddess in the pantheon, so each community would favour their own god/s and goddess/es. With no two communities evolving to have identical beliefs, the individual communities were poorer in terms of faith identity in comparison to the larger monotheistic religions, so they were easily swept into the religion of those who wielded control. 

In the case of Mesopotamia, multiple conquests meant gods and goddesses were assimilated into those of the conquering communities. Over time, elements of these gods/goddesses could be seen in the polytheistic practices of communities scattered across what is now the Levant, ending up in early Judaism. The Hebrew Bible gives numerous examples and hints of what has been before, and the brilliant thing is there is also evidence of its polytheistic ancestry from historical and archaeological sources. 

The polytheistic religion of Ancient Greece inherited elements of Mesopotamian polytheism, eventually being overtaken by Christianity. The conversion of Constantine to Christianity and the expansion of the Roman Empire made Christianity an attractive alternative for many, for others the religion was forced upon them. 

The early Muslim conquests beginning in the 7th century were responsible for the spread of Islam, with the empire expanding rapidly from Arabia into North Africa and southern Europe. As was elsewhere with the rise of Judaism and Christianity, remaining polytheistic communities would have have had difficulty surviving.

I imagine you would find your polytheistic beliefs easier to maintain than it would have been for many pagans and others years ago.