Cain's offering was rejected because he "did it his way" (like Frank Sinatra's song - "I did it MY Way"). There's only two religion's in the world today - that which is by faith according to the will of God and all of the false religions which are works based.

Cain rejected God's prescibed way of salvation. Instead of coming to God on God's terms, Cain rebelled and came on his own terms. Cain's offering probably looked very nice, but it wasn't what God required. So today, many people do wonderful things hoping to be saved by their good deeds. Those who do these good deeds usually want everybody to know of their good deeds too.

Tom F.