Do modern Christians believe that Jesus is God?

All three religions believe in one God (monotheistic).

Christians, in general, follow the Holy Bible --especially the teachings of Jesus Christ-- but not all Christians worship God in the same way. Christians obey many of the teachings or commandments of the Old Testament in addition to the teachings of Jesus in the New Testament. Christians believe that Jesus is the Messiah.

Roman Catholics, the largest of all the Christian denominations see God as a Holy Trinity, that is to say God is singular, but can manifest himself in three ways -- as the Father, the son (Jesus Christ) --who came to earth to absolve the sins of humankind, and the Holy Spirit. The Virgin Mary, the mother of Jesus is believed to have conceived Jesus without sexual relations and remained a Virgin even though she gave birth to Jesus in what is called the Immaculate Conception. Other Christians don't share the same canonical viewpoint as Catholics, hence there are hundreds of different Christian sects.

Jews have the Tanach (Jewish Bible). It is made up of the Torah (5 books of Moshe [Moses]) Nevi'im (Prophets), and K'tuvim (Writings). The Christian Old Testament is based on the Tanach but it was altered to support the teachings of Christianity. The Word 'messiah' is the Anglicized 'moshiach', however, the Christian concept of messiah does not exist in Judaism and Jesus plays no role in Judaism. From the Jewish perspective, Unitarian Christians and Muslims are monotheistic and worship the same G-d as Jews do.

Muslims follow the holy Qu'ran. Mary is mentioned more times in the Qur'an than in the Christian New Testament. Muhammad is the founder of the religion of Islam, a holy prophet and messenger of Allah (as Muslims refer to God). Jesus and the Virgin Mary are mentioned in the Qur'an.