24:15 Seem evil - Unjust, unreasonable or inconvenient. Choose ye - Not that he leaves them to their liberty, whether they would serve God or idols; for Joshua had no such power himself, nor could give it to any other; and both he and they were obliged by the law of Moses, to give their worship to God only, and to forbear all idolatry in themselves, and severely to punish it in others; but it is a powerful insinuation, whereby he both implies, that the worship of God is so highly reasonable, necessary and beneficial; and the service of idols so absurd, and vain, and pernicious, that if it were left free for all men to take their choice, every man in his right wits must needs chuse the service of God, before that of idols; and provokes them to bind themselves faster to God by their own choice. He will - But know this, if you should all be so base and brutish, as to prefer senseless and impotent idols, before the true and living God, it is my firm purpose, that I will, and my children, and servants (as far as I can influence them) shall be constant and faithful to the Lord. And that, whatever others do. They that resolve to serve God, must not start at being singular in it. They that are bound for heaven must be willing to swim against the stream, and must do, not as most do, but as the best do.

Joshua 24:15 Parallel Commentaries

And for Your Fearlessness against them Hold this Sure Sign -- Whenever There Is...
43. And for your fearlessness against them hold this sure sign--whenever there is any apparition, be not prostrate with fear, but whatsoever it be, first boldly ask, Who art thou? And from whence comest thou? And if it should be a vision of holy ones they will assure you, and change your fear into joy. But if the vision should be from the devil, immediately it becomes feeble, beholding your firm purpose of mind. For merely to ask, Who art thou [1083] ? and whence comest thou? is a proof of coolness. …
Athanasius—Select Works and Letters or Athanasius

Covenanting Performed in Former Ages with Approbation from Above.
That the Lord gave special token of his approbation of the exercise of Covenanting, it belongs to this place to show. His approval of the duty was seen when he unfolded the promises of the Everlasting Covenant to his people, while they endeavoured to perform it; and his approval thereof is continually seen in his fulfilment to them of these promises. The special manifestations of his regard, made to them while attending to the service before him, belonged to one or other, or both, of those exhibitions …
John Cunningham—The Ordinance of Covenanting

The First Commandment
Thou shalt have no other gods before me.' Exod 20: 3. Why is the commandment in the second person singular, Thou? Why does not God say, You shall have no other gods? Because the commandment concerns every one, and God would have each one take it as spoken to him by name. Though we are forward to take privileges to ourselves, yet we are apt to shift off duties from ourselves to others; therefore the commandment is in the second person, Thou and Thou, that every one may know that it is spoken to him, …
Thomas Watson—The Ten Commandments