Yes, believed and practised ... still.
Judaism. They still believe in it today, although it has taken many different forms.
The believers in Judaism were (and still are) the Jews.
The diaspora.
They believed in what is now called Judaism.
Adam and Eve are believed to have practiced the religion of Judaism, as they are considered to be the first human beings in the Abrahamic religions, which include Judaism, Christianity, and Islam.
They all believed in one god and believed that good would overcome evil.
Some believed He was the Son of God, the Messiah. Others believed He was a prophet of God while others still believed He was an imposter.
God, the creator of the universe. He was and still is the Supreme Being of Judaism.
Islam, Judaism and Christianity
both.
In fact, Judaism was a missionary religion during the early days of Christianity. We know that Jewish missionaries travelled widely, converting Gentiles. It is believed that in some cases, a missionary would assure potential converts that they need not undergo adult circumcision as long as they believed, but a later missionary would come along and demand to know why the converts were not yet circumcised. We also know that in Medina in the seventh century, Muhammad encountered two tribes that had converted to Judaism. Martin Palmer (the Jesus Sutras) says that from the second century to the twelfth century, Judaism was still an active missionary missionary faith that converted tribes in Arabia and rivalled Christianity in states such as Yemen.
Yes, Judaism is still here. There are around 14 million Jews in the world.