Here are some thinking points about Genesis 3 and 4 --
Satan only has had to use ONE temptation through all time for all of us. It comes in two parts, as you will see with Eve --
"Hath God said...?" -- question God's Word
and then
"...think for yourself..."
Thinking for ourselves is a fine thing unless and until it directly goes against God's Word!
I often see on anti-Christian posts ad other writings that the temptation involved knowledge. That somehow the Bible and God are against knowledge. Nothing could be further from the truth.
What God did not want man to know was the knowledge of EVIL. Man already knew Good, for Adam and Eve communed with God. And God IS Good. So all that was left was evil...
Note, too, that human nature has never changed -- they started out passing the buck and we do it whenever we can get away with it today, too!
"The woman YOU gave me... " (it's really your fault, God...)
"Well, the serpent, he....." (hey, it's not my fault either!)
Note, too, that the promise of a Redeemer is made BEFORE God tells Adam and Eve about the consequences of their disobedience. In the same way, Revelation says Christ is the Lamb slain from the foundation or creation of the world.
I have often wondered WHY Adam ate that fruit? Paul says, in the New Testament, that he was not deceived -- that it was the woman who was deceived. And so I have wondered if Adam was either so in love with Eve that he could not bear the thought of losing her or if Adam thought maybe HE was the one who was supposed to save his wife from the dreadful consequences of her sin. Those are the only two ideas I can come up with. Either way, he was putting his wife ahead of obedience to God, and that ruined everything.
Then came the first blood sacrifice -- done by God when He made clothing of animal skins for the couple. And they are banished from Eden.
A real case of eating yourself out of house and home, eh?...
Chapter 4 -- the first murder, mention of cities and technological accomplishments of the pre-flood civilization(s).
What was the "mark of Cain"? We have no idea, really.
Who did Cain marry? His sister. All the kids of Adam and Eve would have. There were no genetic difficulties preventing close marriages. Incest was not defined or prohibited until the time of Moses. In fact, close marriages were considered preferable for a long time. Abram married Sarai, his half sister. When Isaac was born and then of marriage age, the command of Abraham to his servant was to go back to the land where the rest of the family was and find Isaac a wife from within the family. Isaac's son, Jacob, did the same thing (except he came back with TWO wives and a couple of concubines!). So evidently, from the first, marrying into the family was important.
Were there enough people for cities that early? Look how long they lived (peek ahead to chapter 5). If a woman was only childbearing for a third of her life, that was still for about 300 years! One child every three years is a hundred kids! The first would be married and possibly a parent or even grandparent before the last one was born. It would have been a population explosion unheard of in our time!
Something I did not notice for a long time, though, had to do with murder. Look at the violent reaction to the first murder at the beginning of chapter 4. Now look at how casually Lamech boasts of killing a man or two for some kind of injury in verse 23.
This may be an indication of how evil the world had gotten and how fast it happened.
Last note is the last verse: "At that time men began to call on the name of the Lord." I've heard a lot of explanations about this. The only one that makes sense in context (and I would love some comment on this from those who have studied the Bible) is that the human race in general was now so far from God, that all they could do was 'call on His Name' instead of actually commune with Him.
Anyway, those are some things I have picked up from those two chapters before. I'd love to hear other comments.