Leviticus 17:11

Is in the blood Depends upon the blood, is preserved and nourished by it. The blood maketh atonement Typically, and in respect of the blood of Christ which it represented, and by which the atonement is really made. So the reason is double. 1st, Because this was eating the ransom of their own lives, which in construction was the destroying themselves. 2d, Because it was ingratitude and irreverence toward that sacred blood of Christ, which they ought to have had in continual veneration.