The Old Testament speaks over and over again in opposition to the infidelity of the Hebrews when it came to the worship of "foreign gods". For this reason we know historically that there were influences from the surrounding peoples exerting pressure on the Hebrews. [For a thorough treatment, see The Gospel and its Tributaries by E. F. Scott, for example.] There are small but significant references to polytheism [Deuteronomy 32:7-9] and even to human sacrifice [Jeremiah 19:5]. [An aside: The Valley of Hinnom mentioned in Jeremiah 19:6 was called Gehenna in Jesus' time and is one of the words translated "hell" in some versions of the Bible.]
In fact, if you read the accounts of primitive religions (for example the classic, The Golden Bough) you will see a pattern-- a pattern of ritual practice (either by the people, a priest or a tribal leader) in an attempt to influence the gods for the purpose of gaining favor in the form of good weather, safety, fertility, etc. These attempts frequently involved sacrifices.
The fact that the Hebrews would go to the extreme of burning their children in an attempt to please God (something that God denies he decreed according to Jeremiah) is proof of just how powerful these primitive ideas are. And the fact that attempts to please the gods are pervasive in human culture, and the fact that the Hebrews were influenced by the cultures around them, shows that no "revelation from God" is necessary in order that the Hebrews might have such ideas in their own religion. [I think the important thing in understanding Hebrew religion is to seek out those points which are NOT LIKE the surrounding cultures.]
If you actually read at length from the Old Testament laws on sacrifice, you may be struck by a couple of things that struck me. First are the benefits to the Priests. Basically, the sacrificial system insured not only the support of a priesthood, but that the priests and their families would get to eat the very choicest food morsels--since large portions of the sacrifices were not burned but assigned to the priests to eat. Since the priest wrote the rules, is it any wonder that their personal "perks" are provided for?
Secondly, the actual sacrificial practices are bizarre.
and you shall slaughter the ram, and take some of its blood and put it on the lobe of Aaron's right ear and on the lobes of the right ears of his sons, and on the thumbs of their right hands, and on the big toes of their right feet, and dash the rest of the blood against all sides of the altar.
You can read the whole bloody mess in Exodus 29.
Can anyone seriously believe that God made up this ritual?
Some of the prophets didn't seem to think so. "For in the day that I [the Lord of Hosts] brought your ancestors out of the land of Egypt, I did not speak to them or command them concerning burnt offerings and sacrifices" [Jer 7:22] (If you want to check this out, don't use the NIV translation since it mistranslates this verse. The KJV and any of the standard versions are OK.) Hosea said "For I desire steadfast love and not sacrifice, the knowledge of God rather than burnt offerings. [6:6] This is an important verse because Jesus cites it himself [Mat. 9:13]. The Psalmist [50:8-14] wrote:
I do not accuse you
because of your sacrifices;
your offerings are always before me.
I will take no bull-calf from your stalls,
nor he-goats out of your pens;
for all the beasts of the forest are mine,
the herds in their thousands upon the hills.
I know every bird in the sky,
and the creatures of the fields are in my sight.
If I were hungry, I would not tell you,
for the whole world is mine and all that is in it.
Do you think I eat the flesh of bulls,
or drink the blood of goats?
Offer to God a sacrifice of thanksgiving and make good your vows to the Most High.
If my suggestion is true, that God never ordained a system of animal sacrifices by which the sin of the people was removed, then this notion of purity (familiar in primitive religious systems) as necessary to approach God comes into question. Jesus said "But woe to you, scribes and Pharisees, hypocrites! For you lock people out of the kingdom of heaven. For you do not go in yourselves, and when others are going in, you stop them." [Mat 23:13] I think that any representation of God teaches that God is not immediately present regardless of our state of "purity" falls under this condemnation.
Turning back to culture again... It is indeed a fact that the first Christians were Jews. Jews had a culture of sacrifice and atonement based on their primitive history which was derivative from surrounding religions. When the New Testament writers tried to express the "Jesus event" in a way comprehensible to Jews, they used the language of sacrifice and atonement that meshed with the religious sensibilities of their readers. But Christians are no longer Jews and we need not restrict our understanding of Jesus to a Jewish framework. When Jesus saves us from sin, it is not by erasing numbers from some eternal accounting ledger through being the ultimate child sacrifice, Jesus saves us from sin by freeing us from the artificial barriers between us and God erected by primitive religion and the financial needs of the priestly caste.
And all this is in the scriptures, if you look for it.
A word on inerrancy: Biblical inerrancy forces you to believe that anyone in scripture claiming to speak the words of God is actually speaking the words of God, and if it is the word of God, then all words of God carry equal weight and have equal truth and validity, whether the claim is made by Moses, Jeremiah, Hosea, Jesus or St. Paul. If you drop the inerrant assumption, then it becomes clear, and quickly so, that all of these people weren't saying the same thing. Scripture argues with itself. The central problem with the inerrant assumption is that it makes it impossible to see the revelation of God as a process (since nothing in the past can ever be "wrong").