Leviticus 21:24: The Seriousness of Being God's People

Lest anyone should take the blessing of God lightly, He makes it clear to Moses that his requirements are strict.  The standards for the priests are high, and for the High Priest higher still.  God commands Moses to "Tell Aaron and his sons to treat with respect the sacred offerings the Israelites consecrate to me, so they will not profane my holy name. I am the LORD.  Say to them: 'For the generations to come, if any of your descendants is ceremonially unclean and yet comes near the sacred offerings that the Israelites consecrate to the LORD, that person must be cut off from my presence. I am the LORD." - Lev 22:1-3 NIV

God exhorts his people to "Keep my commands and follow them. I am the LORD.  Do not profane my holy name. I must be acknowledged as holy by the Israelites. I am the LORD, who makes  you holy  and who brought you out of Egypt to be your God. I am the LORD." Lev. 22:31-33 NIV
Then he proceeds to lay out the various feasts they are to observe, the first being the Sabbath.  On an annual basis they are to celebrate the Passover to commemorate when God brought them out of Egypt, the Feast of Firstfruits to acknowledge the first harvest, the Feast of Weeks, the Feast of Trumpets, the day of Atonement and the Feast of Tabernacles to remember that they lived in tents on their journey out of Egypt.
 
In case any of the Children of Israel doubted that God's name was holy and it was not to be profaned, they were told to stone a person in their midst who 'blasphemed the Name with a curse'.  They did as they were told.  This was not just any god they were following.  This was the Name above all Names, the God who bought them and set them apart as holy.