According to Protestants, what is the lesson being taught by scripture when God killed so many men for looking into the Ark?

Many people find a short passage in the Old Testament to be both disturbing and very peculiar; that being 1st Samuel 6:19, > and He (God) smote (killed) the men of Beth-she-mesh, because they > had looked into the Ark of the Lord, even He smote of the people > 50,070 men. The disturbing question is why God would kill so many men for simply looking into the Ark. It seems to be a very peculiar thing to do. One thing is obvious, God is using this event and recording it in His Word as a historical parable. A teaching lesson with a spiritual meaning. What is that meaning? I am not attempting to ask God's motivation for killing these men; but I am asking, what God is teaching through this story? Are there different interpretations of this lesson between the different denominations of Christianity?