[quote=flamingsword]To attain salvation through the Old Testament you needed to observe the law, like ghosty said, but you had to flawlessly follow the law. This is nearly impossible, and in fact only three humans have done so Mary, John the Baptist, and Jesus. The law showed our ancestors that they could not merit salvation themselves and that is where the beauty of Chist’s sacrifice comes in.
When the Judeans had a priesthood, they could get sins forgiven through animal sacrifices. This was the priests purpose (then and now). I do ont know if the forgivensess was as assured as Catholic confession, but it was performed.
The entire mass and its ceremonies / symbolism has roots in this sacrifice (as well obviously as the pass-over).