58 If you do not carefully follow all the words of this law, which are written in this book, and do not revere  this glorious and awesome name - the Lord your God - the Lord will send fearful plagues on you and your descendants, harsh and prolonged disasters, and severe and lingering illnesses. 59-61He will bring on you all the diseases of Egypt that you dreaded, and they will cling to you. The  Lord will also bring on you every kind of sickness and disaster not recorded in this Book of the Law, until you are destroyed. 62-63 You who were as numerous as the stars in the sky will be left but few in number, because you did not obey the  Lord  your God. Just as it pleased the  Lord to make you prosper and increase in number, so it will please him to ruin and destroy you. You will be uprooted  from the land you are entering to possess.

64-68 Then the Lord will scatter you among all nations, from one end of the earth to the other. There you will worship other gods - gods of wood and stone, which neither you nor your ancestors have known. Among those nations you will find no repose, no resting place for the sole of your foot. There the Lord will give you an anxious mind, eyes weary with longing, and a despairing heart. You will live in constant suspense, filled with dread both night and day, never sure of your life. In the morning you will say, “If only it were evening!” and in the evening, “If only it were morning!”—because of the terror that will fill your hearts and the sights that your eyes will see. The Lord will send you back in ships to Egypt on a journey I said you should never make again. There you will offer yourselves for sale to your enemies as male and female slaves, but no one will buy you. Deuteronomy 28:53-68 New International Version

We come at last to the final part of this long chapter of fearful things that were to come upon the nation of Israel if they turned their back on God who had so mercifully rescued them from their condition of slavery in Egypt, and given them wonderful promises of protection and care. What was the real cause of the disasters that God would send? (vs 58)

Apart from treating His good commandments casually, even with contempt, the danger was that they would one day forget the uniquely glorious name of their Saviour. The Old Testament tells us that when God made Himself known to Moses (who wrote Deuteronomy) while he was caring for his father-in-laws flock, Moses asked God what His name was. And God replied: “I AM WHO I AM.” And God said, “Say this to the people of Israel, ‘I AM' has sent me to you.’” God also said to Moses, “Say this to the people of Israel, ‘The Lord, the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you.’ This is my name for ever, and this is how I am to be remembered throughout all generations.” (Exodus 3:14-15) 

While that sounds strange in English, that name in the Hebrew language was YHWH – which has been pronounced as 'Jehovah' or 'Yahweh'. This was the same God who had made Himself known to Israel's ancestors Abraham, Isaac and Jacob and distinguished God from the many false gods people worshipped in those days. Later, when the ruler of Egypt kept refusing to let the Israelites go God said to Pharaoh through Moses “By now I could have put out my hand and struck you and your people with pestilence, and you would have been cut off from the earth. But for this purpose I have raised you up, to show you my power, so that my name may be proclaimed in all the earth.” (Exodus 9:15-16)

That was what Israel was meant to do by loving God and keeping His commandments. The blessings that God would have poured out on the nation would have made God's name glorious to the whole world. And that's why their not revering His name was so serious, and why God would send the sort of diseases they had seen in Egypt, and eventual captivity again, upon them. After telling Israel they were to have no other gods, and not to make idols, God also said “You shall not take the name of the Lord your God in vain, for the Lord will not hold him guiltless who takes his name in vain.” (Exodus 20:7) That meant they were not treat God's name irreverently, or behave in ways that dishonoured His name and brought it into disgrace. This is just as true today for anyone who loves the Lord Jesus Christ. Our desire should be to bring honour to God's name by how we live.