God required the sin offering to be burnt outside the sanctuary. 

Ezekiel 43:21

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“Then you shall also take the bull of the sin offering, and burn it in the appointed place of the temple, outside the sanctuary.” Ezekiel 43:21

The place for burning the carcass of the animal sacrifice was outside the sanctuary. The sanctuary was considered a Holy place of life and atonement, not a place where dead carcasses would be brought in. At the same time, the blood of the animal sacrifice was brought into the sanctuary to atone for sin. Under the system of Jewish laws, the high priest brought the blood of the slain animals into the sanctuary as a sacrifice for sin, and then the bodies of the animals were burned outside the city. 

When Jesus Christ took sin upon Himself, as He hung on the altar of the Cross as the Lamb of God, He experienced death. In that sense, His body was not within the Holy sanctuary of life and cleansing, but He suffered outside the sanctuary. In that same light, the blood He shed was brought into the sanctuary, our body, to atone for our sin to cleanse us and give us life. “For the bodies of those beasts, whose blood is brought into the sanctuary by the high priest for sin, are burned without the camp. Wherefore Jesus also, that he might sanctify the people with his own blood, suffered without the gate.” Hebrews 13:11-12

“For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.” 2 Corinthians 5:21

What can wash away my sin?
Nothing but the blood of Jesus;
What can make me whole again?
Nothing but the blood of Jesus.

Oh! precious is the flow
That makes me white as snow;
No other fount I know,
  Nothing but the blood of Jesus.
[Church hymn]

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….to you who do not hold to her teaching and have not learned Satan’s so-called deep secrets,
I will not impose any other burden on you, except to hold on to what you have until I come.
I am coming soon. Hold on to what you have, so that no one will take your crown.
Revelation 2:24-25, 3:11