This may sound like a stupid question, but I've been mulling this over in my head for awhile.
If people in Old Testament times were saved the same way we are (by placing their faith in the Messiah - they, looking ahead, we looking back) why were the animal sacrifices needed at all? Why didn't God simply instruct them to place their faith in the promised Messiah to come?
The shedding of the blood of bulls and goats wouldn't get sins forgiven. Abraham simply believed and he was declared righteous.
So why the sacrifices?
The terms of the Sinaitic covenant were very clear!
While faith was a crucial aspect of salvation in every era it would be a true mistake to believe that more than a tiny minority of Israelites were ever saved.
Also, in terms of the Sinaitic covenant no one was ever saved by animal sacrifice - animal sacrifice offered only a limited atonement as in only specified sins at a specific point in time were atoned for - that was why they had to be repeated over and over again. No sin offering in terms of this covenant ever offered a blanket unconditional atonement.
As New covenant believers, we now understand the role that animal sacrifice played:
It gave everyone a tangible grip on the consequences of sin - sin cannot be atoned for apart from death and the shedding of blood;
Sin has a price! One cannot atone for sin in terms of the Sinaitic covenant apart from sacrificing (or first buying) the best livestock one has. The cost of losing (or having to buy) livestock for sin offerings was considerable for a largely pastoral population! God knew that the Israelites were a proud and rebellious people (seems not much has changed for all races and groups!) and so sin, and the consequences and price of sin, were decisively implanted into minds of the all Israelites. It was this aspect that Paul references in Romans 7:13 where he says this: "
But sin, that it might appear sin, was producing death in me through what is good, so that sin through the commandment might become exceedingly sinful." Rom 7:13.
The Israelites always knew that more was required, that they could not, of themselves, give, in order to access salvation and heaven. We now know that the fulness of salvation is offered by the sin sacrifice and shed blood of Jesus Christ. In this sense the animal sacrifices under the Sinaitic covenant were nothing more that a picture, or shadow, of what was to come in the ministry of Jesus Christ!
Nothing has changed today in the sense that sacrifice for sin and the shedding of blood is STILL required for salvation!
The ONLY difference is that in the crucifixion of Jesus Christ, His sacrifice and shed blood allows an offer of once-for-all salvation, not the limited atonement of the Sinaitic covenant. And, just as it was for believing Abraham, this offer of salvation is offered by grace through faith Eph 2:8-10.