The Mark of Cain

Genesis Chapter 4

There are a few interesting things in this chapter. 

Why did Cain kill Abel? according to the Bible it was the act of a jealous brother after God accepts Abel's offerings but no Cain's. I'm not entirely sure why this should be - some would say Cain bought fruit but Abel bought the best firstborn lambs, and that Abel's offering was higher value or more special somehow. Personally I don't know

Once Cain has killed Abel and is banished by God he says “whoever finds me will kill me”. 

People ask “Who did Seth and Cain marry?” and the comment Cain makes here is telling – The bible is not telling the whole story here, there are obviously other humans around. God gives Cain a mark that others recognise as divine protection.

We also see the starting of entertainment with Jubal and Tubal-Cain starting the love of metallurgy with the apparent discovery of Bronze.

We also see the start of religion “at that time men began to call on the name of the Lord”