Nephilim means as it has been traditionally taught to be angels who came down and procreated with women by marrying and having children with them, but this is a false teaching. Only God can incarnate His angels into human form for the purpose of His ministry, not for procreation.
Genesis 6:4 There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
The way I read this verse is that there were giants in the earth in those days before the flood and also after the flood when the sons of God (Godly line of Seth named in Genesis 5) as they all had sons and daughters, but not all of these sons and daughters obeyed God and fell away from Him and let's not forget the ungodly line of Cain that some of these sons and daughters might have married into Cain's line came in unto the daughters of men and they bare children to them, as some had the hereditary autosomal dominant pituitary gene such as AIP that produces Nephilim/giants the same became mighty men which were of old, men of renown. (this gene had to start with Adam).
Strong's Exhaustive Concordance - Nephilim
Part of Speech: noun masculine
Transliteration: Nephilim
Phonetic Spelling : nef-eel
Definition: "giants", name of two people, one before the flood and one after the flood
By this definition these angels would have to have come down two different times to marry the daughters of men. Once before the flood and again after the flood, but we only find this one time in Genesis 6:1, 2.
There is no such thing as a half angel, half human hybrid called Giants. Nephilim is just a name given to giants that we read about in scripture and even those that are living today being over 6 feet and taller.
Rephaim - race of giants Genesis 14:5-7; Deuteronomy 3:11-13; 2 Samuel 21:16-20, Og the king of Bashan was the last of the Rephaim
Anakim - race of giants Numbers 13:33; Deuteronomy 2:10; 9:2 Anak son of Arba Joshua 15:13 descendent of Canaan, son of Ham
Emim - the proud deserters, terrors, race of giants Genesis 14:5-7; Genesis, 19:37; Deuteronomy 2:10, 11 descendants of Canaan, son of Ham
Zuzim/Zamzummim's the evil ones, roaming things Genesis 14:5-7, 19:38 Deuteronomy 2:20 descendants of Canaan, son of Ham
It's just like the name Lucifer/Satan/prince of darkness/Beelzebub/father of lies and many more names given to this fallen angel. Satan is nothing more than a fallen angel that goes to and fro in the earth, and from walking up and down in it as he still has access to the throne room of God as he stands accusing the brethren as Jesus sits and makes intercession for us. Satan is the opposite of God's goodness as his evil hierarchy includes the third of the angels that have followed after him as he sends them throughout the earth for his destructive purpose in man, 1 Peter 5:8.
The term "sons of God" has multiple meanings in the Bible like humans who have a special relationship with God like the nation of Israel who are called God's first born son in Exodus 4:22. Solomon was called the son of God, 1Chronicles 28:6, as well as all of us that are in Christ are sons/daughters of God, Galatians 3:26.
Gen 6:1 And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them,
Gen 6:2 That the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose.
Gen 6:3 And the LORD said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years.
Gen 6:4 There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
Angels are spirit form and have no genitals or sperm in order to get a woman pregnant. Angels have no gender (Matthew 22:30) and are innumerable (Hebrews 12:22). They are incarnate in human form at times (Genesis 18:2-8) for the purpose of ministry.
It's only a man's theory or interpretation of Genesis 6:1-4 as many hold this theory about angels getting women pregnant as being true, but yet no evidence in scripture other than this is found in the book of Enoch in which was written after the death of Enoch.
Having identified the "sons of God" as "godly line of Seth" is a false teaching. There's every biblical evidence against it and nothing for it:
1. "Call on the name of the Lord" in Gen. 4:26 is invalid reasoning. Calling the name of the Lord doesn't make the caller holy or righteous, God values godly work, not empty words.
Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven. (Matt. 7:21)
2. "Sons of God" in Rom. 8:14 is invalid reasoning. In the context of Rom. 8:12-17, children of God are led by the Holy Spirit and ADOPTED through Christ. That context doesn't exist in the pre-flood world of Gen.6. NT definition of "children of God" is NOT applicable to OT context.
For as many as are
led by the Spirit of God, these are sons of God. For you did not receive the spirit of bondage again to fear, but you received the Spirit of adoption by whom we cry out, “Abba, Father.”The Spirit Himself bears witness with our spirit that we are children of God, and if children, then heirs—heirs of God and
joint heirs with Christ, if indeed we suffer with Him, that we may also be glorified together.
3. "Sons of God" are evil heavenly beings in Satan's company, they're under God's judgement. There's everything UNgodly and nothing godly in them.
I said, “You are gods, And all of you are children of the Most High. But you shall die like men, and fall like one of the princes. (Ps. 82:6-7)
Now there was a day when the sons of God came to present themselves before the Lord, and Satan also came among them. (Job. 1:6)
4. In the context of Gen. 6, all mankind was full of wickedness, so much so that it had grieved God to made the decision of drowning them all in a global flood. There's no presumed distinction between Seth's descendants and Cain's, everyone was evil to the core except Noah and his family.
Then the Lord saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually. (Gen. 6:5)
5. The conclusion of "angels don't procreate" based on Matt. 22:30 is invalid reasoning. In Matt. 22:30 it specifically says angels of God in HEAVEN, that's their "proper domain", that puts a hard limit on that conclusion. When that limit is no longer in place, neither does this conclusion. As a matter of fact, the context of Gen. 6 was set not in heaven, but on EARTH, where angels manifest in human form with human physiological functions including procreation and eating, as shown in Gen. 19:5 and 18:8. Therefore, "angels don't procreate" is no longer established when angels leave their "proper domain" and go down to earth. Angels in heaven don't marry or give in marriage, but they can do so as humans on earth.
And the angels who did not keep their proper domain,
but left their own abode, He has reserved in everlasting chains under darkness for the judgment of the great day; (Jude 1:6)
So he (Abraham) took butter and milk and the calf which he had prepared, and set it before them (Lord God and the two angels); and he stood by them under the tree
as they ate. (Gen. 18:8)
Now the
two angels came to Sodom in the evening, and Lot was sitting in the gate of Sodom ... (Gen. 19:1)
“Where are
the men who came to you tonight? Bring them out to us that we may
know them carnally.”(Gen. 19:5)
For as in the days before the flood, they were eating and drinking,
marrying and giving in marriage, until the day that Noah entered the ark ... (Matt. 24:39)
This distinction between heavenly form and earthly form is also taught by Paul. When mortal human beings are resurrected, they are transformed from terrestrial beings to celestial beings; therefore, when angels reveal themselves to men on earth, they must manifest as terrestrial beings, not celestial beings because celestial bodies are incompatible with earthly environment.
There are also celestial bodies and terrestrial bodies; but the glory of the celestial is one, and the glory of the terrestrial is another. (1 Cor. 15:40)
6. "Sons of God" are able to present themselves before God as they did in Job 1:6, yet no human being can see God and live. That indicates heavenly nature of the "Sons of God" and precludes any earthly nature.
But He said, “You cannot see My face; for no man shall see Me, and live.” (Ex. 33:20)
.