Who were the "giants" mentioned in the Bible?

Another theory that I've heard is that "sons of God" refers to those who were members of the primordial religion, and that "sons/daughters of man" refers to those who had apostatized and turned to a false religion. This would yield the interpretation of men were marrying those not of their faith.

_{I apologize for a lack of citation, but I thought it was an interesting idea that hadn't been put forward yet. I'll try to find a reference and will update my answer if I do}

The phrase "sons of God" appears 4 times in the Old Testament, twice in the passage in Genesis, and twice in the book of Job. Job's passages are plainly angels, so in the context of the Old Testament, the Genesis references should be understood first as angels unless there is sufficient reason to rule it out.

Angels have the ability to take on human form (see Genesis 19:5-8). In the case of these fallen angels, they apparently took on human form complete with tweaked human DNA coded for extreme size and aggressiveness. Angels in heaven do not marry, but it doesn't say that they are incapable of taking on human form and marrying. God's angels who did not rebel have no use or need for human females, so they don't marry. Human females are made to correspond to the human male who is made in the image of God, and this explains their appeal to the fallen angels who were themselves created as "sons of God". (Male and female are together God's image; but man is the direct image while woman is an indirect image according to 1 Corinthians 11:7)

These giants are called "men" in Genesis and elsewhere, indicating that regardless of their satanic origin, God considered them human, and dealt with them and judged them accordingly.

The groups listed by Moses in Deuteronomy are noted for their size. Og was a remnant of these groups, and his bed was about 13.5 feet long by 6 feet wide. This would make him roughly twice as tall as an ordinary person today. This cannot be explained by giantism today, since giantism is debilitating and does not result in "mighty men". These giants were superior athletes.

The spies refer to the sons of Anak as having great size (albeit exaggerated), and by that they claim that they were "Nephilim". So the spies are interpreting the Nephilim in Genesis as meaning giants in terms of size. If they were twice the height of normal men as Og's bed seems to indicate, then their fear and comparisons are understandable (though inexcusable in light of God's power).

There are 5 tribes of giants mentioned in the Bible after the Flood: Emims, Zamzummims, Horims, Avims, and Rephaims. They lived around the perimeter of Canaan. According to Genesis 6:4, they were produced the same way the Nephilim were produced before the Flood. Emims, Horims, and Rephaims (possibly the Zamzummims also) were defeated in the first wave of Chedorlaomer's invasion in Genesis 14:5-6 before he was defeated by Abraham. The giants were weakened in number by this attack. Later the Emims were eradicated from Ar by the Moabites, the Zamzummims were finished in Ammon by the Ammonites, the Horims were driven out of Mt Seir by Esau, and the Avims were finished off by the Caphtorites. Caphtor was a descendant of Mizraim (Hamitic, from Egypt). According to Josephus, their cities were destroyed in the Ethiopic war and so they migrated to Phillistia where they encountered and defeated the Avims.

The Rephaims included Og and the Anakim, the sons of Anak who was a son of Arba. Arba himself may have been one of the first post-flood hybrids since his father is not cited. These were defeated by the Isrealites as they invaded the promised land.

Joshua 11:22 states that there were giants left in Gaza, Gath, and Ashdod. This explains the later appearance of Goliath from Gath. Goliath was roughly 9.5 feet tall. A few generations removed from Og's size of approximately 13.5 feet tall, the original hybrids were likely the largest, and their descendants got smaller as they interbred.

Jude verse 6 refers to the punishment of angels; the judgment of some angels is reserved for the end in Revelation 12:7-8.

Matthew 22:30 Jesus said that the angels of God in heaven do not marry. He said nothing about what the devil's angels (see Rev 12:7-8) do when they are on Earth.

Genesis 6:4 states that there were "giants in those days, and also after that", and identifies this as a result of the aforementioned interbreeding. Giants after the Flood include 5 tribes mentioned in the Bible. It is highly unlikely that the interbreeding of believers and non-believers after the Flood would produce giants. If the production of giants requires a daughter of Cain and a son of Seth, then a daughter of Cain would have to have married a son of Noah. If that son was Ham, then all of Ham's sons should be giants. The tribes of giants lived around the Canaanites, but none of them are listed as the offspring of Canaan or Ham or anyone else in Genesis 10. This is best explained by the idea that they were generated by fallen angel/human hybridization, so their male lineage was not through a son of Noah.

The Hebrew term Nephilium does mean "fallen ones", but I see no particular reason why this indicates that they are/were angels rather than fallen men. Rendering them fallen angels seems inconsistent with everything else we know about the nature of angels vs men.

Scholarship is widely divided on this issue reading many different things into the very few verses we have that refer to them directly. When in doubt, I believe we need to use our understanding from other parts of scripture and even of the world in general to make sense out of it.

We generally know that even among the created order here on earth things don't just change species. Species can't inter-breed. In the heavenly realms we have spirit beings that do not have associated matter in the created universe. They are allowed to manifest themselves in a way that interacts with men, but we also know that such things fall generally under the sovereignty of God. Even Satan is not allowed to take specific action on earth without God's express permission.

Taking these into consideration I find it inconsistent with what we know of God to have given fallen angels such permissions. If such a thing really were to have happened it would seem likely that we would have more references to it than two verse with an obscure word that can be translated "giants" just easily as "angels".

There are several other propositions about how these could be a race of men with an exceptional strand of gene (very much inside the realm of what we know of creation) that gave them exceptional size and stature. There are also explanations for where they lived (I've heard explanations about a mountain region) that can explain the language about them having 'come down'.*

Taken as a whole I think it is a better hermeneutic to not assume something that goes against our established understandings of both our world and the rest of Scripture without a much more explicit text that says they must be spirit beings.

I find the references cited by Jonathan unconvincing. That we will be LIKE the angels in specific attributes does not mean that we will actually be angels. Humans, even as souls in heaven, have specifically different properties than angels. Lifespan issues extend well beyond the scope of just the Nephilim and are explained other ways. God didn't just change the lifespan of said Nephilim, we know that he did that for humans. The connections to God's spirit I find be speculative at best. They COULD fit, but add nothing to drive the argument that they MUST be angels because it would fit just as well if the scope was only humans.

* _{I plan on finding these but it's too late tonight, saving for an edit.}

The Nephilim are fallen Angels, or descendants of such.

First we need to understand that the "sons of God" mentioned in Genesis are angels, and here's how we do that. The Hebrew words used here are Ben 'elohiym.

Ben Literally means a 'descendant of'. So sons, grandsons, translated to son.

'elohiym can be translated into a few different words. rulers, judges, divine ones, angels, gods.

You can see that the scholars behind the NKJV have translated these words to say "sons of God", while the new international version scholars have translated the meaning to say "the angels."

Satan presents himself with the other angels

We know that Satan is an angel and we see him presenting himself with the other angels before God, in the book of Job.

Job 2:1 NKJV

Again there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them to present himself before the LORD.

Job 2:1 NIV

On another day the angels came to present themselves before the LORD, and Satan also came with them to present himself before him.

We shall be called sons of God, equal to Angels

We can also expand on this understanding with the following verses, in order to know for sure that these sons of God are spiritual beings filled with the holy spirit.

Luke 20:36 NKJV

nor can they die anymore, for they are equal to the angels and are sons of God, being sons of the resurrection.

Romans 8:14 KJV

For as many as are led by the Spirit of God, they are the sons of God.

These particular angels in Genesis are fallen Angels

Genesis 6:4 NIV

The Nephilim were on the earth in those days—and also afterward—when the sons of God went to the daughters of humans and had children by them. They were the heroes of old, men of renown.

The Hebrew word for Nephilim is N@phiyl which originates from the word Naphal which means "to fall, fallen."

We can see further connection and description of these fallen angels in Numbers

Numbers 13:33

We saw the Nephilim there (the descendants of Anak come from the Nephilim). We seemed like grasshoppers in our own eyes, and we looked the same to them.”

These three men seemed to have lived for a long time, as we see their lives spanning past the exodus, when they were finally driven out of their land and we don't hear about them anymore.

Judges 1:20

And they gave Hebron to Caleb, as Moses had said. Then he expelled from there the three sons of Anak.

This gives us a lot of insight into Genesis 6:3, when God says that His spirit shall not strive with man forever. He will shorten the life of mortal men to 120 years.

Genesis 6:3 (NKJV)

3 And the LORD said, “My Spirit shall not strive with man forever, for he is indeed flesh; yet his days shall be one hundred and twenty years.”

It seems clear to me that God is talking about these fallen angels when He says "My Spirit."

As a Hebrew speaker, I may have a chance to contribute here.

The Hebrew word used to describe the giants is Nephilim, spelled נפילים, which comes from the verb נפל - which means "to fall".

The most common explanation in the Jewish tradition is that those are either fallen angels, or the sons of such angels, born to human wives. In both cases they are referred to as evil, and unlike in many other ancient mythologies (e.g. the Greek Mythology), those fallen angels do not have any supernatural powers except their size. It is mentioned that they lived for 120 years - maybe in order to show that they are not immortal.