Deuteronomy 8:19

19 Forsooth if thou forgettest thy Lord God, and followest alien gods, and worshippest them in (thine) heart, and honourest [them] withoutforth, lo! now I before-say to thee, that thou shalt perish utterly; (But if thou forgettest the Lord thy God, and followest foreign, or other, gods, and worshippest them inwardly, and honourest them outwardly, lo! I now say to thee beforehand, that is, I warn thee, that thou shalt utterly perish;)

Deuteronomy 8:19 Meaning and Commentary

Deuteronomy 8:19

And it shall be, if thou do at all forget the Lord thy God,
&c.] Either the mercies they received from him, not acknowledging they came from him, but ascribing them to themselves; or their duty to him, to whom they were so greatly obliged: and walk after other gods, and serve them, and worship them; which would be to forget him indeed, forsaking his worship, and giving homage and adoration to idols, which is what is intended by these expressions:

I testify against you this day that ye shall surely perish;
by one judgment and calamity or another, as the sword, famine, pestilence, and captivity; there being nothing more provoking to God than idolatry, which so much detracts from his honour and glory: and which besides, in such a people, so highly favoured of God, it argued the basest ingratitude.

Deuteronomy 8:19 In-Context

17 lest thou wouldest say in thine heart, My strength, and the might of mine hand, hath given all these things to me. (lest thou shouldest say in thy heart, My own strength, and the might of my own hand, hath given me all these things.)

18 But think thou upon thy Lord God, that he hath given strengths to thee (to become prosperous), that he should fulfill his covenant, of which he swore to thy fathers, as this present day showeth. (But rather, remember the Lord thy God, that it is he who hath given thee the power to become prosperous, in order to fulfill his covenant which he swore to thy fathers, as he doeth in this present day.)

19 Forsooth if thou forgettest thy Lord God, and followest alien gods, and worshippest them in (thine) heart, and honourest [them] withoutforth, lo! now I before-say to thee, that thou shalt perish utterly; (But if thou forgettest the Lord thy God, and followest foreign, or other, gods, and worshippest them inwardly, and honourest them outwardly, lo! I now say to thee beforehand, that is, I warn thee, that thou shalt utterly perish;)

20 as [the] heathen men perished, which the Lord did away in thine entering, so also ye shall perish, if ye shall be unobedient to the voice of your Lord God. (as the heathen shall perish, whom the Lord shall do away when thou shalt enter into the land, so also ye shall perish, if ye do not obey the voice of the Lord your God.)