Because Worshiping God Isn't "Have It Your Way"

Sometimes it's hard for me to grasp and know how to handle the fact that, as J. Ligon Duncan III says on p. 57 of Give Praise to God, "God is dangerous to those who are careless in worship, however sincere." The first part of that sentence makes sense; God created us to worship Him, therefore we do. But the second part and the practical application and outworking of this concept is what is difficult. Nadab and Abihu were never told not to offer "strange fire," yet God struck them down for doing so. Uzzah put his hand on the ark to steady it when the oxen stumbled, and God struck him down for touching the ark. Sometimes these reactions seem extreme, because the hearts of the offenders were right; they were sincere. 

God takes worship very seriously. While He may not be striking people down left and right today for not worshiping Him correctly, I wonder how many of us would be guilty of wrong worship, and God, in His great mercy, spared us. He owns us, and can do with us as He pleases. It's easy for us to forget our smallness, but when we look at God in all His greatness, power, and goodness, we remember.