You seem to equate the religion of ancient Israel with Christianity. How can you justify this?

The faith of ancient Israel centered on their belief in a coming Messiah. When we see, as Scripture clearly shows us, that Jesus was that Messiah, then the only basic difference between that faith and Christianity was that they looked forward to the coming of the Lord while we look back to it. If we define Christianity as faith in Christ, then the believing Israelites—going all the way back to Moses’ day—were Christians.

The one glaring difference is the sacrificial system that God put in place at that time. The book of Hebrews, though, explains how the whole sacrificial system was a temporary arrangement put in place to help them understand the need for the shedding of blood as the remission for sin. It kept the faith alive through the 15 centuries that lapsed before the Messiah came and gave Himself as the final sacrifice. The sacrifices pointed to Christ, the true Messiah. So what we have are pre-Christ and post-Christ Christians.