The First Commandment. it cleaves to anything else, of which it expects more good and help than of God, and does not take refuge in Him, but in adversity flees from Him, then you have an idol, another god.
In order that it may be seen that God will not have this commandment thrown to the winds, but will most strictly enforce it, He has attached to it first a terrible threat, and then a beautiful, comforting promise which is also to be urged and impressed upon young people, that they may take it to heart and retain it:
[Exposition of the Appendix to the First Commandment.] For I am the Lord, thy God, strong and jealous, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate Me; and showing mercy unto thousands of them that love Me and keep My commandments.
Although these words relate to all the commandments (as we shall hereafter learn), yet they are joined to this chief commandment because it is of first importance that men have a right head; for where the head is right, the whole life must be right, and vice versa. Learn, therefore, from these words how angry God is with those who trust in anything but Him, and again, how good and gracious He is to those who trust and believe in Him alone with the whole heart; so that His anger does not cease until the fourth generation, while, on the other hand, His blessing and goodness extend to many thousands lest you live in such security and commit yourself to chance, as men of brutal heart, who think that it makes no great difference [how they live]. He is a God who will not leave it unavenged if men turn from Him, and will not cease to be angry until the fourth generation, even until they are utterly exterminated. Therefore He is to be feared, and not to be desisted.
He has also demonstrated this in all history, as the Scriptures abundantly show and daily experience still teaches. For from the beginning He has utterly extirpated all idolatry, and, on account of it, both heathen and Jews; even as at the present day He overthrows all false worship, so that all who remain therein must finally perish. Therefore, although proud, powerful, and rich worldlings [Sardanapaluses and Phalarides, who surpass even the Persians in wealth] are now to be found, who boast defiantly of their Mammon, with utter disregard whether God is angry at or smiles on them, and dare to withstand His wrath, yet they shall not succeed, but before they are aware, they shall be wrecked, with all in which they trusted; as all others have perished who have thought themselves more secure or powerful.
And just because of such hardened heads who imagine because God connives and allows them to rest in security, that He either is entirely ignorant or cares nothing about such matters, He must deal a smashing blow and punish them, so that He cannot forget it unto children's children; so that every one may take note and see that this is no joke to Him. For they are those whom He means when He says: Who hate Me, i.e., those who persist in their defiance and pride; whatever is preached or said to them, they will not listen; when they are reproved, in order that they may learn to know themselves and amend before the punishment