It seems as if the author is saying that there were no animal sacrifices before Sinai...but there were:
Gen 4:3 And in process of time it came to pass, that Cain brought of the fruit of the ground an offering unto the LORD.
Gen 4:4 And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the LORD had respect unto Abel and to his offering:
Gen 4:5 But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.
Gen 8:20 And Noah built an altar unto the LORD; and took of every clean beast, and of every clean fowl, and offered burnt offerings on the altar.
Gen 22:13 And Abraham lifted up his eyes, and looked, and behold behind him a ram caught in a thicket by his horns: and Abraham went and took the ram, and offered him up for a burnt offering in the stead of his son.
Maybe I'm wrong about his premise, but animal sacrifice had been a means of worshiping God for quite a while.
Outstanding response.
But giv’em a little bit of time to figure out which scriptures to mangle and I am sure they’ll have some lame rebuttal affirming the author’s incompetent assertion regarding animal sacrifice.
Very first animal sacrifice in scripture: [Genesis 3:21] Unto Adam also and to his wife did the LORD God make coats of skins, and clothed them.
What ever inhabited those skins prior to this event indeed had their lives sacrificed so Adam and Eve could have a "covering for their sin".....so to speak.