The old or the sinful nature was inherited from the first man [Adam] before we were born again. Salvation is a gift of God. While He ascended He gave gifts to men. He took captivity [Sheol] captive (Romans 6:18).
They [i.e. all the souls of Old Testament saints] were not able to enter heaven because they did not yet receive salvation or the nature of God which is the new man that is perfectly righteous made in the image of God. So only the Gospel was preached to those spirits in prison, including all those [i.e. disobedient saints] who died during Noah's flood time (Eph 4:9-10; 4:24; 1 Peter 3:20; 4:6), that they might live according to God in the spirit [which is the new man that is born again] (1 Peter 4:6).
Without Holiness no man will see God (Heb 12:14). So only David also spoke about his soul being in Sheol [The abode of the dead] and his confidence in the Messiah that 'He will not leave David's soul in sheol.'(Psalm 16:10).
In the flesh how were they judged? According to Romans 6:23, they all died physically [This was the wages of sin], But the Gift of God [i.e. free gift of salvation] they received is eternal life in Christ Jesus our Lord. Even in Luke 16:22, the Bible speaks about Lazarus carried by the angels to Abraham's bosom where people were comforted and rich man was tormented in the flame and a gulf existed between them. This was Sheol.
Even to the criminal who was crucified when he said to Jesus, "Lord, remember me when you come in to your kingdom". Jesus said to him, "Assuredly I say unto you, today you will be with me in paradise." He was speaking about the abode of the dead as paradise because first He descended in to the lower parts of the earth (Eph 4:9) and then He ascended far above all heavens, that "At the name of Jesus every knee should bow,...of those under the earth." (Philippians 2:10).
The Son of man sitting at the right hand of power, is His Kingdom that was coming upon those in heaven and those in earth and those under the earth that He might fill all things (Mark 14:62). Jesus preached the Gospel to the spirits in prison before His resurrection, So only when He rose from the grave, many of the Old Testament saints also rose from their graves and were seen by many in Jerusalem (Isaiah 26:19 ; Matt 27: 52-53; 28:2).
"by whom [the Spirit] also He ((Jesus) Christ ) went and preached to the spirits in prison, who formerly were disobedient, when once the divine longsuffering waited in the days of Noah, While the ark was being prepared, in which a few, that is eight souls were saved through water." (1 Peter 3:19-20).
Who were these people for whom God waited in the days of Noah who were formerly disobedient?
These were the Godly people whom God separated, to bring out the Messiah at the right time. They themselves were expecting God to send the redeemer [Messiah] who will restore their life from sin and will restore the fellowship with God as before the fall of man. So only Lamech named or gave the name Noah to him when he was born, Lamech himself expected rest from the curse of the ground. So he named him Noah which means rest (1 Peter 3:19, 20; Genesis 5:28-29).
After Lamech begot Noah, he lived 595 years and had many sons and daughters. Totally he lived 777 years and he died. This is a number of perfection which symbolically shows that he produced a line of people whom God considered perfect by separating them for himself. These people were God fearing line of people who lived during that period of time. This is the reason God had differentiated the line of Cain from the line of Adam's God fearing line in chapter 4 and 5 of Genesis. Noah was 500 years old when he begot Shem, Ham and Japheth and they married and had God fearing wives and they lived along with the Noah and his wife.
Now how many of them were truly God fearing [i.e. Obedient to the voice of God by their life styles]? Eight.
How God considered them God fearing? The answer starts when God starts to separate and define these people at the end of 4th chapter of Genesis. "...Then men began to call on the name of the Lord." (Gen 4:26). It all started with the new son Seth which means appointed in the literal Hebrew, who was born to Eve instead of Abel [Which means Breath or Nothing] when Adam knew his wife again. This was the place where God appointed a people of Faith. After this Seth begot a son named Enosh. As the Bible says from there on this Godly generation began to call on the name of the Lord.
The Bible says in Genesis 6:1, "...When men [Unbelievers or ungodly immoral people] began to multiply....". In verse 2, "...the sons of God [God fearing obedient men] saw the daughters of men [Unbelievers], that they were beautiful; ...". In the Bible Adam is called as the son of God to denote his direct relationship with God and him being in the image and likeness of God (Luke 3:38; Genesis 1:26-27; 5:1-4). Naturally these sons of God must be the God fearing descendants of Adam.
The God fearing people did two great mistakes,
(i) They took wives for themselves from unbelievers. [Note: The plurality of the language (wives not wife)]
(ii) They chose all those women based on their own will apart from the will of God. [There was no covenant commitment and monogamy (Luke17:26-27)].
In Gen 6:3, in other words God said, 'I will not compel them to obey, by My Spirit, to do things the right way, So that they will not be destroyed with unbelievers.'
The Bible says in Gen 6:4, "There were giants [Heb.Nephilim, fallen or mighty ones] in those days...". When the believers and unbelievers got mixed up, their children were the mighty men [violent men] who were of old, men of renown. Here the word nephilim in Hebrew was the same word which was used for giant size strong men who lived in Canaan's land (Num 13:32, 33). Does that mean that angels were having relationship with women to produce these men in Canaan's land? No! Not at all. But in context in the next word, "Then the Lord saw....that the intent of the thoughts of his heart was only evil continually." (Genesis 6:5).
God was not concerned about their size but God saw the intent of the thoughts of man. That means because of an unholy alliance between God-fearing obedient people and line of Cain or ungodly violent people, man has corrupted himself and everyone had got mixed up except one man where the filtered Godly genealogy stops and God said "it is time for judgment because the earth was filled with violence through them." (Genesis 4: 9, 13). Besides this evidence, Jesus Himself has told in Matthew 22:30, "For in the resurrection they neither marry nor are given in marriage, but are like angels [which includes fallen and the good angels (Job 1:6,12;1 Samuel 19:9;1 Kings 22:19-23;Luke 1:19)] of God in heaven." In other words, Jesus has plainly said angels cannot procreate by having intercourse like humans. What more evidence we need, to say that the Sons of God were just human beings in Noah's time and not angels.
Comparing the 4th and 3rd verse of Genesis 6, We can easily say that the genetics of man was so blessed even after he got cursed in Eden, he was so strong that he lived for hundred's of years. God specially has given the lifespan of the genealogy of Noah to emphasize that they were strong and extraordinarily healthy. When they got mixed up, they produced men with such blessings that they were giants on earth and afterward these men who were mighty in strength, size and men of renown who had special skill and intelligence. By that time, the devil have started to use the blessings of God to fill the earth with violence. Because these Godly people did not obey the voice and promptings of the Spirit of God, He cannot let these disobedient people to be used by the devil, So God shortened their lifespan so that they will not fill the earth with violence.
In spite of God shortening their lifespan they began to multiply and fill the earth. But the problem is because of their disobedience their heart was filled with violence and through them in all the earth. In other words the earth was becoming a living hell. This state of the earth pushed God to judge the earth.
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