Sacrifice

...God did by sending his own Son in the likeness of sinful man to be a sin offering.

And so he condemned sin in sinful man,

 in order that the righteous requirements of the law might be fully met in us,

who do not live according to the sinful nature but according to the Spirit. (Romans 8:3b-4) 

     Sin kills. It may not kill all at once, but it kills. The sin offering required of the Jews made that clear. The sinner had to kill an animal that had not sinned in order to make up for their sins. It couldn't be just any sacrifice. The more socially visible and responsible the sinner, the bigger the sacrifice had to be. They had to examine it and make sure that it was perfect. No defects allowed. Imagine examining a goat to make sure it was perfect, all the while knowing that it had done nothing and that either it or you had to die because of something you did. It had to be sacrificed by a priest who was also physically whole. No defects allowed. The priest also had to be ceremonially clean. (I have to wonder if anyone ever asked the priests, or whether they took it for granted.) Examined, perfect, innocent animal dying at the hands of a perfect, ceremonially innocent priest so you could continue to live.

       Then Jesus came. Because He was examined, perfect and innocent, He could be the sacrifice.  He was not dead, and so could offer His life. Because He was a man and both perfect and clean, He could offer the sacrifice. Because He is God, He did not stay dead. He met the requirements of the Law that we could not, but once they have been met, the Law is replaced by something better: the Spirit.

       There are those who say that all religions are the same, that other ways than Jesus are just as good. What they have in common is that they all leave that sacrifice up to us. Christianity is the only one that makes the sacrifice for us. It is the only one whose leader came back from the dead to prove it works. It is the only one that I know of that gives the Spirit as a seal or proof.