John Gill Bible Commentary

There shall no strange god be in thee,.... Or in the midst of thee, owned and worshipped as God; or in thine heart, for whatever engrosses the affection, or a man puts his trust and confidence in, that he makes his god, and is a strange one: thus, if any friend or relation, father or mother, wife or children, are loved more than God, they are set up as such in his place; thus the epicure, that seeks the gratification of his carnal lusts, makes his belly his god; and the covetous man his money, in which he trusts, and therefore is called an idolater; and the self-righteous man his righteousness, on which he depends for salvation: hence we read of idols set up in the heart, from which they are disengaged in conversion, and kept from, Eze 14:7. neither shall thou worship any strange god; only the Lord God is to be worshipped, Mat 28:19 and there is but one God; though this is to be understood not to the exclusion of the Son and Spirit, who are with the Father the one God, and to be worshipped equally with him, and are; see Mat 28:19.