This is a bit of a thorny topic as most folks believe the Nephilim are the offspring of the fallen angels which were giants. I disagree.
When researching the Word, one must take into account several things regarding the word or phrase or topic under scrutiny. The word 'nephilim' was translated in the KJV as 'giants', because, I assume, they did not know what the word meant. Hence everyone thinks that the Nephilim are the hybrid offspring of spirits and humans which were giants.
But the Hebrew word 'nephilim' literally means 'the fallen ones'. I contend that these were the fallen angels themselves, the sons of God, who fell from grace, fell from Heaven and fell to earth. Hence, 'the fallen ones'. Nephilim.
But let us widen the study from Genesis 6. We are discussing fallen angels here. So to better understand our quest, we look at many of the places in Scripture and the Book of Enoch where it speaks of angels falling from Heaven to earth. This will provide a 'scope' of the topic of fallen angels and better inform us. To save time, I shall list these off quickly:
"How art thou fallen from Heaven O Lucifer..." Isa 14:12
"I beheld Satan as lightening fall to earth..." Luke 10:18
"I saw a star (angel) fall from Heaven onto the earth..." Rev.9:1
"And the stars (angels) of Heaven fell unto the earth as figs falling..." Rev.6:13
"Behold a star fell from Heaven..." Book of Enoch 86:1
"I saw many stars fall and cast themselves from Heaven..." Enoch 86:3
"He seized the first star that had fallen from the Heavens..." Enoch 88:1
"The seven heads are seven kings...five have fallen, one is and the other is not yet come..." Rev.17:9,10
(That is, these seven are Nephilim. This is why it says 'five are fallen' because they are 'fallen angels').
So the interesting thing to notice here is that everywhere it talks of angels coming from Heaven to earth, it uses the words 'fall' or 'fallen' to describe the event. This is not a coincidence. This is the proper usage of words by the Holy Spirit to communicate an idea.
God could have used other words such as descended; alighted; came down; landed; flew down; appeared etc. But He did not. He uses the word 'fallen'. This gives us the overall picture regarding evil angels falling to earth and ties us back to the Nephilim of Genesis 6; the 'fallen ones'. I know some will say that the Greek Septuagint translates this word as 'gigantes'. But Greek was not in existence and only came along way after the events of Genesis 6 which was a mere 800 to 1,000 years or so after Adam and Eve in the garden.
So we must defer to the inspiried Word of God for direction and this informs us that those evil spirit men who manifested on earth way back in the dim, distant past on Mount Hermon were the Nephilim; the fallen ones. Thus there is a reason why Genesis 6:4 says:
"The Nephilim were ON THE EARTH in those days..."
The inference being that prior to this they were not on the earth. They were in Heaven and had not yet left their 'first estate'. Jude 6
"And the angels which kept not their own estate, but left their own habitation..."
'Habitation' here is oiketerion. The only other place this word is found is in 2 Corinthians 5:2 which speaks of our spiritual bodies. Thus Jude is telling us that when the fallen angels left their original home, Heaven, and fell to earth, they forsook their spiritual bodies or lost some of their spiritual abilities, and became manifest on earth in full view of humankind.
So let us be technically and grammatically accurate when we speak of the evil fallen angels. These are the Nephilim who became the heroes of old, the men of renown in Greek and Roman mythology which speaks of the exploits of these gods of legend. Sure it speaks of the giants also. But these were a mere sideshow compared to the supernatural, powerful spiritual beings who manifested on planet earth in plain sight and caused all the sin and violence in those days which filled the earth with bloodshed and precipitated the Flood.
And, "as it was in the days of Noah...so shall it be".
Dr. Patrick Heron is the author of Apocalypse Soon and The Nephilim and the Pyramid of the Apocalypse. You can find more information about Patrick's latest book, The Return of the Antichrist and the New World Order, at his website www.nephilimapocalypse.com.