The Jewish writer Philo of Alexandria lived during the time Christianity began, yet his writings don't match our preconceived notions of what Jewish thought at that time should have been. However, he was a spokesman for Judaism and his writings were popular enough to have survived, therefor any study of Christian origins has to take Philo's writings into account. Keep in mind also that the monotheistic rabbis didn't appear until later centuries.
Philo was not a monotheist, but rather believed in a second god called the Logos or the Word. This means many Jews of his time believed in a second god as well. This is not surprising since the Jews of Alexandria already had the Wisdom of Solomon.
Thy all powerful Word leaped from heaven, from the royal throne, into the midst of the land that was doomed, a stern warrior carrying a sharp sword of thy authentic command, and stood and filled all things with death, and touched heaven while standing on the earth. (The Wisdom of Solomon 18:15-16)
The destroyer with the great sword had originally been Yahweh (Exodus 12:12, 29). Philo elsewhere describes the Logos in terms used for Yahweh, meaning that for Philo and his Alexandrian community, Yahweh was the Word. Early Christian writers such as Clement of Alexandria and Theodotus equated Jesus with the Logos (see also the beginning of the Gospel of John), which isn't surprising since Jesus is equated with Yahweh (Lord) throughout the New Testament.
Philo also refers to the Logos as King, Shepherd, High Priest, and Firstborn Son among other titles. The Logos was the son of the Most High (Elyon). Philo also equates Logos with Wisdom, even though Logos was male and Wisdom female. This presents no difficulty for Wisdom seems to be the female aspect of Logos just as she is the female aspect of Yahweh in the Old Testament.
The writings of Philo and the apocalypticists clearly point to an alternate form of Judaism which was polytheistic. Just because Deuteronomistic monotheism later came to dominate Jewish thought doesn't mean it always had.
In the Targums (Jewish translations/commentary on the Bible written in Aramaic) the word Memra is used to refer to the Word of God. The Word of the New Testament is described in the same way as Philo's Logos and the Memra of the Targums (John 1, 1 John 1:1-2, Revelation 19:11-16, Hebrews 4:12, 2 Peter 3:5-7).
In the early centuries of Christianity, a main focus of rabbinic Judaism was to discredit the idea that there were two gods. According to the Mekhilta of R. Ishmael, this idea apparently came about due to two different appearances of Yahweh in Exodus. In Exodus 15:3, Yahweh is a man of war, indicating that he is a young warrior. In Exodus 24:10, Yahweh is giving Law, the activity of an old man. R. Ishmael tries to explain this apparent contradiction away by explaining that Yahweh can appear in different forms and he cites Daniel 7 as an example. It's a strange example to cite, however, since Daniel 7 portrays two distinct gods, the young warrior Yahweh and the Ancient of Days Elyon.
Yahweh created sea monsters in Genesis 1:21, but some scriptures point to an earlier myth in which he battled them (Letter of Manasseh 3, see also Isaiah 51:9 in which Yahweh kills the sea dragon Rahab). Yahweh created the stars in Genesis 1:16 simply as sources of light, yet they sing in Job 38:7 along with the other sons of god. Although they are centuries later, gnostic writings appear to preserve the earlier form of Judaism including talk of sea monsters and angels.
Instead of making the usual assumption that gnosticism is a heretical form of Christianity, Margaret Barker takes a close look at the texts and finds that gnosticism has more in common with pre-Deuteronomic Judaism. Gnosticism is exactly what you'd expect to find if a group of Jews rejected the monotheistic reform and held onto the earlier beliefs. They grew to view Judaism as the enemy and the god of the Jews as evil, although they still believed in a good god. According to The Apocryphon of John, the Great Archon seduced Eve who then gave birth to two sons, the good Yave and the evil Eloim (Apocryphon of John II:1:24). Basilides taught that Christ came to destroy the God of the Jews.
There are many varieties of Gnostic thought, but in general, they believed that the god which created the world was not the only god, although he foolishly thought he was. There was another more powerful god, much like the relationship between El Elyon and Yahweh. One gnostic text points out that Yahweh admits he isn't the only god when he says that he is a jealous god. If there was no other god, why would he be jealous? (Apocryphon of John II:1:11-13)
The Gnostics also speak of a female aspect of god called Sophia who shared a lot in common with the Wisdom of the Bible. She was said to be the tree of knowledge in the garden of Eden (Apocryphon of John II:1:22, Hypostatis of the Archons II:4:94, 1 Enoch 32:3-6, Proverbs 3:18).
The early Christians identified El Elyon with the Father and Yahweh with the Son, or Jesus. The pseudo-Clementine writings contain a debate between Simon Magus and Simon Peter in which Simon Magus claims the God of the Jews was not the Most High God. Simon Peter counters that while each of the seventy two nations has a being called a god ruling over it, they are really angels mistaken for gods.
Early Christians, including Paul, referred to the God of the Jews, Yahweh, as the Son of God and identified him with Jesus. The Father was El Elyon, the Most High God, who created Yahweh. Anytime the Old Testament referred to Yahweh, the Christians took it as a reference to the pre-existent Jesus. In his Dialogue with Trypho, Justin cites numerous scriptures from the Old Testament which support the two gods theory.
The distinction between the Father and Son had begun to blur by the time of Irenaeus of Lyons and Clement of Alexandria, but Christians still believed there were two separate gods in the Old Testament. Hippolytus of Rome believed the Ancient of Days in Daniel was the Most High God, while the Son of Man was Jesus. Novatian read the Old Testament the same way.
Unlike modern translators, Eusebius read the Hebrew of Psalm 91:9 correctly: "You, O Yahweh, are my refuge, you have made Elyon your dwelling place." (Proof IX:7) Two distinct gods are clearly referenced, yet modern readings are based on what the translators think it should have said. Eusebius goes on to demonstrate that the Hebrew of Psalms 45:7 indicates the the Anointed One is a second god, not a priest: "Thou hast, O God, loved justice and hated impiety: therefore in return, O God, the highest and greater God, Who is also thy God hath anointed thee." (Proof IV:15)
The Angel in the Book of Revelation was Yahweh. He is the first and the last (Revelation 1:17). He could permit people to eat from the tree of life (2:7). He had the sharp sword of judgement (2:12). He was the Son of God (2:18). He had the seven spirits of God (3:1). He was also the Scribe of the Book of Life (3:5). Reveleation 3:14 (Amen, the faithful and true witness, the beginning of God's creation) could be a reference to Amon who assisted in the creation (Proverbs 8:30).
Philo associated his Logos with the center of the menorah (which had only seven candles in the Old Testament, as opposed the the nine candles of the modern day menorah). The early Christian document The Shepherd of Hermas described the Son of God having three angels on his left and three on his right (Hermas Sim. ix:12:8) The psuedo-Cyprianic text The Threefold Fruit of the Christian Life tells us the Son of God was one of the seven angels (216-219). An engraved amythyst has been discovered bearing the names of the seven archangels: Raphael, Renel, Uriel, Ichtys, Michael, Gabriel, and Azael. Ichtys was the common acronym for Jesus Christ Son of God Saviour.
The Ascension of Isaiah has the second Lord (Jesus) sit on the right side of the throne of the first Lord (Elyon) with the angel of the Holy Spirit sitting on the left (Ascension of Isaiah 11:32-33). In 2 Enoch 24:1, this Holy Spirit is the angel Gabriel. Jewish tradition (Genesis Rabbah 78:1) held that while the other angels were insignificant, Michael and Gabriel did not change. There was even an early version of the trinity which was composed of Christos, Michael and Gabriel which can be recognized in epitaphs, amulets, amphorae, and seal stones dating back to the fourth century.
Origen speaks of a similar Jewish tradition in which God has a masculine aspect called the Word and a feminine aspect called the Spirit. The canonical Gospels don't tell us who declared Jesus the beloved son during the baptism, we simply assume it was the Father. However, the Gospel of the Hebrews (now lost, but quoted by Origen and Jerome) states that the Holy Spirit is the Mother of Jesus and it was she who declared Jesus her son during the baptism.
Jesus is sometimes identified with Gabriel (Epistle of the Apostles, the Sibylline oracles) and sometimes identified with Michael (Shepherd of Hermas, Revelation 12:7, 11:16). Jesus was known as the Angel of Great Council to the early Christians (LXX Isaiah 9:6, Novatian, Theodotus, Origen, Eusebius). Methodius called him chief among the archangels. Melito and Justin also called Jesus an Angel.
In Revelation 14:1, the saved have the name of god written upon their foreheads. According to Ezekiel 9:4, this mark was a tau, which looks like X in the old Hebrew and Samaritan scripts. This is mentioned in the Talmud (Horayoth 12a) as the shape of a Greek chi. Early Chrisitans put this sign upon their foreheads, showing they identified Yahweh and Christ.
The early Christians prayed to Jesus as if he were Yahweh (1 Corinthians 16:22, Didache 10:6). Several early versions of John 1:18 read "the only begotten GOD who is in the bosom of the Father" instead of "only begotten Son" (Codex Sinaiticus, Codex Vaticanus, parts of Irenaeus and Origen). Barker goes on to quote numerous New Testament passages which name Jesus as God. Jesus is called the Savior in the New Testament, while the Old Testament constantly refers to Yahweh as the Savior.
In 2 Esdras 13, the Son of God rises from the sea and destroys the wicked by breathing fire. There are a couple cryptic references to a deity named Righteousness (Isaiah 1:21,26) thought by some to be the Canaanite deity Zedek, but Righteousness could be another of Yahweh's titles. The name Melchizedek is also related.
2 Corinthians and the Epistle to the Hebrews both imply that Jesus was present at the Exodus. Two of the most important early manuscripts of Jude, verse 5 (Codex Vaticanus and Codex Alexandrinus) actually read, "Jesus saved a people from the land of Egypt." This isn't surprising after reading the numerous passages in the New Testament which clearly identify Jesus as Yahweh.