The Bible speaks of a race of giants who roamed the Earth before the great flood of Noah's day. Some Bible versions call them “giants”(Darby Translation, Douay-Rheims, King James Version, The Message, etc.) while others call them “Nephilim”(American Standard Version, World English Bible, Holman Christian Standard Bible, New American Standard Bible, etc.). According to Strong's Hebrew Lexicon, the word “Nephilim is defined as follows:

World #5303
nphiyl nef-eel' or nphil {nef-eel'}; from 5307, properly, a feller, i.e. a bully or tyrant:--giant.

BIBLICAL SUPPORT

The Bible tells of these Nephilim, revealing that these were the offspring of angels, essentially becoming demigods to the Earth's population during the time of Noah:

Genesis 6:4

The Nephilim were in the earth in those days, and also after that, when God’s sons came in to men’s daughters. They bore children to them. Those were the mighty men who were of old, men of renown.

Note how this states these giants existed in those days (the days of Noah) " and after that". It is important to note this bit because many believe that the deluge of Noah's day completely destroyed these angel/human hybrids, whereas this Scripture shows that these “sons of God” continued to mate with women after Noah's day (though apparently not on the same scale). This is supported in other Bible books which contain accounts that happened many generations after the deluge:

Numbers 13:33

There we saw the Nephilim, the sons of Anak, who come of the Nephilim: and we were in our own sight as grasshoppers, and so we were in their sight.”

Deuteronomy 2:10-11

The Emim lived therein before, a people great, and many, and tall, as the Anakim: (11) these also are accounted Rephaim, as the Anakim*; but the Moabites call them Emim.

*The word “Anakim” is Hebrew plural for “Anak”, mentioned in the previous Scripture above

Deuteronomy 3:11

For only Og king of Bashan remained of the remnant of the Rephaim; behold, his bedstead was a bedstead of iron; isn’t it in Rabbah of the children of Ammon? nine cubits was its length, and four cubits its breadth, after the cubit of a man.

*A cubit is about 18 inches. This means that his bed was about 14 feet long and about 7.5 feet wide.

1 Chronicles 20:6

There was again war at Gath, where there was a man of great stature, whose fingers and toes were twenty-four, six on each hand, and six on each foot; and he also was born to the giant

The idea of angels having sexual relationships with humankind is a crime in God's eyes, as it fits in the crime of going after “strange flesh”:

Jude 1:6

(6) Angels who didn’t keep their first domain, but deserted their own dwelling place, he has kept in everlasting bonds under darkness for the judgment of the great day. (7) Even as Sodom and Gomorrah, and the cities around them, having, in the same way as these, given themselves over to sexual immorality and gone after strange flesh*, are set forth as an example, suffering the punishment of eternal fire.

*"Strange flesh" is flesh other than one's own, such as animal flesh or hybridized angelic flesh. See detailed discussion regarding “strange flessh” under the subheading “Bestiality” in chapter 15, titled “Human Intimacy”

PARALLELS TO MYTHOLOGY

The results of these flesh-and-angel unions created a hybrid between the spiritual realm and the physical realm. Such unusual progeny would be larger and have abilities and power unlike any normal human being due to the angelic traits being passed onto the offspring. It is thought that this supernatural race of offspring originated the lore of gods from ancient mythology. Consider the following:

In ancient Greek and Roman mythology gods came down from the heavens to mate with women, who in turn gave birth to supernatural hybrid humans who possessed amazing abilities and/or powers. This gave rise to legends such as Hercules, Achilles, and the twin boys Romulus and Remus, among others.

Interestingly, these mythologies also have the common idea of a “king” of the gods: Zeus was the king of the Greek gods and Jupiter was the king of the Roman gods. Many who study this lore believe that these different versions of the “king of the gods” all relate to Satan: Since these god-kings rule over the other gods, and since Satan is seen as the ruler of the demons (angels who've sinned), this parallel is drawn.

It is also interesting to note that Satan desired to become a god (Isaiah 14:12-20). Through the guise of being the king of all other gods he would have been able to make his desire come true to a large extent. This ruse would easily lead innumerable people away from the worship of the True God as they, instead, installed him and his fallen angels as gods to be worshiped. This is the way in which these fallen angels have forged the pantheons of gods: Greek gods, Roman gods, Norse gods, Hindu gods, Wiccans gods, Shinto gods, and all other groups who have honoured multiple gods. And when we celebrate Valentine's day by using the Roman god Cupid we are actually honouring a demon (This is why many Christians avoid Cupid decorations on Valentine's day). And when we speak the name of the holiday of “Easter” we are speaking the name of the goddess Eastre, honouring yet another demon (This is why many Churches prefer to use the title “Resurrection Sunday” instead).

This is exactly why the Bible states that acts of idolatry are, in truth, the worship of demons:

Deuteronomy 32:17 The sacrificed unto devils, not to God, to gods whom they knew not, to new gods that came newly up, whom your fathers feared not.

Psalms 106:37 Yea, they sacrificed their sons and their daughters unto devils

1 Corinthians 10:19-20 What say I then? That the idol is any thing, or that which is offered in sacrifice to idols is any thing? But I say that the things which the Gentiles sacrifice, they sacrifice to devils, and not to God. And I would not that ye should have fellowship with devils.

Revelation 9:20 And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils and idols of gold, and silver, and brass, and stone and of wood, which neither can see, nor hear, nor walk.

...And the Bible also forewarns that in latter times people will be deceived into following the doctrines of demons (a.k.a. Devils):

1 Timothy 4:1-3 Now the Spirit speaketh expressly that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils; speaking lies in hypocrisy, having their conscience seared with a hot iron; forbidding to marry and commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth.

We can see the influence of such demonic teachings today, as many religious groups enforce celibacy or require abstinence from meat, teach doctrine that is not in the Bible, and frequently behave in very hypocritical ways.

CLOSING COMMENTS

Suffice it to say, Satan and his fallen angels have done a successful job in insinuating themselves as gods in our world. Beginning with the Nephilim, things have progressed to the point to where we now have an array of Greek, Roman, Norse, Hindu, Wiccan, Shinto and tribal gods who are worshiped throughout the world. These pagan gods are honoured in almost every facet of our lives: In the names of the months ("January"), the names of the days of the week ("Thursday"), in holiday symbols ("Cupid"), and the names of the planets in our solar system ("Jupiter"). We have a chocolate candy company named after the god of war ("Mars"). We name our children after the goddess of beauty ("Venus Williams"). We name our space missions after gods ("Apollo"). A book of maps is named for a god ("Atlas"). We name our automobile companies after gods ("Saturn"). We name our web companies after gods ("Juno"). We name our sports companies after gods ("Nike"). Yeah, I could go on and on – Clearly, Satan has saturated our world with his demonic gods so thoroughly that we don't even blink when any of the above-mentioned things are mentioned.

This is something that won't be taken lightly when Jesus Christ returns to gather His true worshippers.