The Bible is a summary of God's revelation of Himself and how He interacts with humanity. Everything you need for living a life on God's terms (rather than mankind's terms) is in His everlasting word, comprised of 66 books. There are no contradictions, only misunderstandings and mysteries.
Moses wrote the book of Genesis (origins or beginning) around 1400 to 120 B.C. while he was in the wilderness. Essentially, it is the story of redemption at its very core. Chapters 1 through 11 provide a broad overview of creation to the death of Jacob's son, Joseph.
Beginning at chapter 12, Moses relates 10 origin stories that complete the Old Testament narrative. As the book proceeds, Moses begins to narrow the book down and place more emphasis and focus on specific topics.
Humanity was growing more corrupt because of the inherited sin of Adam and Eve in the Garden of Eden, specifically when they ate of the forbidden fruit from the tree of knowledge of good and evil.
Beginning in verses chapter 6, verses 1 and 2 we read: "When man began to multiply on the face of the land and daughters were born to them, the sons of God saw that the daughters of man were attractive. And they took as their wives any they chose" (Genesis 6:1-2, ESV).
Seems harmless, right? God wanted man to be fruitful and multiply. But a closer examination of the Hebrew and Aramaic words, and the context in Genesis 6, reveal something more sinister that remains controversial but nevertheless true to this day.
Sons of God is translated "angels" (Job 1:6; 2:1 and 38:7). Remember, before the creation of the universe, God had already cast Satan and one-third of the angels down to Earth because of their rebellion. This is why Satan was in the Garden with Adam and his equal helper, Eve.
These angels were demons. "But angels are spirits!" you say. Yes, they are. But we also know that they are able to take on the appearance of men in physical form. We observe this in Genesis 19:1-5 when two angels appeared in Sodom and Gomorrah and wicked men wanted to have sex with them. We also see angels appear in human form in Mark 16:5.
Demonic angels were able to do the same as God's holy angels, as we see in verses 2 and 3. What we have here then is demons possessing the wicked descendants from Cain - regular men! They then had sex with women, and the women bore children who were called Nephilim.
The Bible describes Nephilim thus: "The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of man and they bore children to them. These were the mighty men who were of old, the men of renown" (Genesis 6:4, ESV).
These Nephilim were mighty men. Giants. Huge and powerful men. Scary! We hear about them later as Israel is about to enter into the Promised Land.
But God was not pleased with the continued sin of humanity. We read: "The Lord saw that the wickedness of man was great in the earth, and that every intention of the thoughts of his heart was only evil continually" (Genesis 6:5, ESV).
Sound familiar? This is true today. Judgment will come again.
But God brought about His judgment on sin in the form of the Great Flood in Genesis 6:5-6. Verses 5-6 are linked to verses 1-4. We know about this story of the flood. Even pagans have heard the story.
This judgment was but an example of the final judgment of God in Revelation and 16 times elsewhere. These specific demons mentioned above were cast into the pit so that they would not repeat their grievous evil.
Matters that are not pertinent to foundational doctrines (teachings) of the Christian faith may be debated in a spirit of love.
Some teachers believe demons cannot procreate with humans. This stems from Matthew 22:30: "At the resurrection people will neither marry nor be given in marriage; they will be like the angels in heaven" (NIV).
This verse does not imply that “angels are not able to marry.” Instead, it reveals a truth wherein that angels do not marry. Big difference.
The verse is making reference to the “angels in heaven.” However, it is not referring to fallen angels, who do not care whatsoever about God’s created order of things, and who consistently and actively pursue various means to disrupt God’s plan. The truth that God’s holy angels do not marry or engage in procreation does not mean that the same holds true of Satan and his demonic companions.
God cannot look on sin and not judge it. His justice is right and pure, unlike the world's perverted sense of justice. Our worldly justice may be translated "just us" - that is - it is not fair towards the poor and downtrodden, but rather it excuses the crimes and sins of the wealthy and powerful.
But a final judgment is coming. Make no mistake about it.
"Then I saw a great white throne and Him who sat upon it, from whose presence earth and heaven fled away, and no place was found for them. And I saw the dead, the great and the small, standing before the throne, and books were opened; and another book was opened, which is the book of life; and the dead were judged from the things which were written in the books, according to their deeds. And the sea gave up the dead which were in it, and death and Hades gave up the dead which were in them; and they were judged, every one of them according to their deeds" (Revelation 20:11-13).