Hebrews 10:1-4 meaning

The Pauline Author is doubling down on the insufficiency of the law. It is described as a shadow of something greater in the future: For the Law, since it has only a shadow of the good things to come and not the very form of things, can never, by the same sacrifices which they offer continually year by year, make perfect those who draw near (v 1). 

The sacrifices made under the law involved killing animals, which doesn't really take away sins, and were performed every year for the people of Israel. These sacrifices under the law were inadequate by nature (a shadow of the good things to come) by the need to repeat them (year by year) and by the materials used for them (bulls and goats).

The Pauline Author asks the question, that if these sacrifices based on the Old Testament law were really sufficient, why were they continued? Otherwise, would they not have ceased to be offered, because the worshipers, having once been cleansed, would no longer have had consciousness of sins? (v 2). If they were good enough to make perfect those who draw near to God, the Israelites would have stopped making sacrifices. They would have been free of consciousness of sins.

The Pauline Author is not saying the Law was bad or stupid (it was given by God, commanded to be followed). He is saying that the Law showed sin but did not remove sin: But in those sacrifices there is a reminder of sins year by year (v 3). Christ's sacrifice is superior because His sacrifice removed sin. The sacrifices under the law pointed to the coming of the perfect sacrifice — Christ. Animal sacrifices served as a reminder of sins, telling the Israelites every year, "You are unholy, you are sinful, but God is holy."

The Pauline Author's underlying reason for pointing out the inferiority of animal sacrifices is to make it clear to the Jewish believers receiving this letter that their religious practice was a symbol of something they already had. Religious practice is not something to rely on. It points to the reality of Christ. Since Christ was the perfect atoning sacrifice for sins forever, there is no necessity to continue to make animal sacrifices. However, there is also no prohibition. 

We see that even in the Messianic Kingdom, when Christ reigns on earth, that animal sacrifices will still take place (Ezekiel 43:18-27). Even Paul continued to follow Jewish customs. In Acts 28:17 when Paul gets to Rome, where he will be martyred, he tells the leaders of the Jews that he has never done anything against the customs of the fathers, meaning that he has followed the Jewish ceremonies. 

In Acts 21:22-26, Paul interacts with the Jewish elders of the Jerusalem church, who invite Paul to practice a Jewish custom involving a vow to demonstrate that he still keeps the law. And Paul complies, to show he supports the Jews following the ceremonial laws. However, the passage also emphasizes that the church elders acknowledged what was decided in the Acts 15 council, that the Gentiles were not bound by Jewish custom. Therefore they agreed with the key finding in Acts 15:11, that all are saved by grace, Jew and Gentile alike.

The book of Hebrews is a warning letter, and the primary problem seems to be that the Jewish believers were drifting away from the purity of the gospel, walking by faith in the risen Jesus. Instead, they had begun depending on Jewish practices. But religious practice is insufficient. To depend on religious practices makes Jesus secondary. Walking by faith means walking in the power of the risen Christ, not relying on our own observance to religious custom: For it is impossible for the blood of bulls and goats to take away sins (v 4).

The Pauline Author writes that the Law can never...make perfect those who draw near. This idea of making us perfect or making our faith perfect is prevalent throughout Hebrews. The word for perfect in Greek is "teleiosi," which means "to complete, or finish, or fulfill something." Earlier, the Pauline Author declared Christ's purpose in saving us was to bring "many sons to glory" (Hebrews 2:10). He restored our relationship with God so that we could become sanctified, mature, and share His reward of rulership over the coming kingdom. 

This is the perfecting (or completing) of our salvation; it is the fulfillment of what we were saved to. We were saved from separation from God to a restored relationship with Him, that we would serve Him obediently (through suffering too, just as Christ did). This is what the life of a believer is meant to be. The law was incapable of perfecting anyone in this manner. Only the obedience of faith can do that.