No, it is monotheistic.
Greco-Roman Paganism/Polytheism.
Polytheism, Roman style.
Greco-Roman Paganism/Polytheism.
Polytheism.
Both are practically the same with only some lite differences. The Romans pretty much copied Hellenic polytheism and simply changed the names.
If you mean traditional Roman Polytheism then no, Europe was entirely Christian by the renaissance, if you mean Roman Catholicism then yes.
The belief in many gods and goddesses is called polytheism. It is a common feature of many ancient religions, including Greek, Roman, and Hindu polytheism. Each deity is often associated with specific aspects of life or the natural world.
NO
Roman government: Political Position - Pragmatism Cultural Position - Polytheism
Polytheism has always gone on and it is still lasting today. Polytheism is still practiced today by Wiccans (who have a Lord and Lady), some branches of Hinduism (although some see the gods as manifestations of a single deity) and some African tribal religions. Polytheism was supplanted in the Roman Empire by the fourth century CE but it began to wane much earlier.
In the Roman Empire, with the birth of Jesus.