Happy they that have this one Lord for their God; for they have but one master to please, but one benefactor to seek to. It is better to have one fountain that a thousand cisterns, one all-sufficient God than a thousand insufficient ones.
We are here taught concerning the duty which God requires of man. It is all summed up in this as its principle, Thou shalt love the Lord thy God with all thy heart. He had undertaken to teach them to fear God; and, in pursuance of his undertaking, he here teaches them to love him, for the warmer our affection to him the greater will be our veneration for him; the child that honours his parents no doubt loves them. Did ever any prince make a law that his subjects should love him? Yet such is the condescension of the divine grace that this is made the first and great commandment of God's law, that we love him, and that we perform all other parts of our duty to him from a principle of love. My son, give me thy heart. We must highly esteem him, be well pleased that there is such a Being, well pleased in all his attributes, and relations to us: our desire must be towards him, our delight in him, our dependence upon him, and to him we must be entirely devoted. It must be a constant pleasure to us to think of him, hear from him, speak to him, and serve him. We must love him, (1.) As the Lord, the best of beings, most excellent and amiable in himself. (2.) As our God, a God in covenant with us, our Father, and the most kind and bountiful of friends and benefactors. We are also commanded to love God with all our heart, and soul, and might; that is, we must love him, [1.] With a sincere love; not in word and tongue only, saying we love him when our hearts are not with him, but inwardly, and in truth, solacing ourselves in him. [2.] With a strong love; the heart must be carried out towards him with great ardour and fervency of affection. Some have hence though that we should avoid saying (as we commonly express ourselves) that we will do this or that with all our heart, for we must not do any thing with all our heart but love God; and that this phrase, being here used concerning that sacred fire, should not be unhallowed. He that is our all must have our all, and none but he. [3.] With a superlative love; we must love God above any creature whatsoever, and love nothing besides him but what we love for him and in subordination to him. [4.] With an intelligent love; for so it is explained, Mark xii. 33. To love him with all the heart, and with all the understanding, we must know him, and therefore love him as those that see good cause to love him. [5.] With an entire love; he is one, and therefore our hearts must be united in this love, and the whole stream of our affections must run towards him. O that this love of God may be shed abroad in our hearts!