My suggestion is Thomas Paine's excellent "Common Sense". It was written in 1776. The full text can be found here - but this is a taster -
"Government by kings was first introduced into the world by the Heathens, from whom the children of Israel copied the custom. It was the most prosperous invention the Devil ever set on foot for the promotion of idolatry. The Heathens paid divine honors to their deceased kings, and the christian world hath improved on the plan by doing the same to their living ones. How impious is the title of sacred majesty applied to a worm, who in the midst of his splendor is crumbling into dust!
As the exalting one man so greatly above the rest cannot be justified on the equal rights of nature, so neither can it be defended on the authority of scripture; for the will of the Almighty, as declared by Gideon and the prophet Samuel, expressly disapproves of government by kings. All anti-monarchical parts of scripture have been very smoothly glossed over in monarchical governments, but they undoubtedly merit the attention of countries which have their governments yet to form. "Render unto Cæsar the things which are Cæsar's" is the scripture doctrine of courts, yet it is no support of monarchical government, for the Jews at that time were without a king, and in a state of vassalage to the Romans.
Near three thousand years passed away from the Mosaic account of the creation, till the Jews under a national delusion requested a king. Till then their form of government (except in extraordinary cases, where the Almighty interposed) was a kind of republic administered by a judge and the elders of the tribes. Kings they had none, and it was held sinful to acknowledge any being under that title but the Lord of Hosts. And when a man seriously reflects on the idolatrous homage which is paid to the persons of Kings, he need not wonder, that the Almighty ever jealous of his honor, should disapprove of a form of government which so impiously invades the prerogative of heaven.
Monarchy is ranked in scripture as one of the sins of the Jews, for which a curse in reserve is denounced against them. The history of that transaction is worth attending to.
The children of Israel being oppressed by the Midianites, Gideon marched against them with a small army, and victory, thro' the divine interposition, decided in his favour. The Jews elate with success, and attributing it to the generalship of Gideon, proposed making him a king, saying, Rule thou over us, thou and thy son and thy son's son. Here was temptation in its fullest extent; not a kingdom only, but an hereditary one, but Gideon in the piety of his soul replied, I will not rule over you, neither shall my son rule over you. THE LORD SHALL RULE OVER YOU. Words need not be more explicit; Gideon doth not decline the honor, but denieth their right to give it; neither doth he compliment them with invented declarations of his thanks, but in the positive stile of a prophet charges them with disaffection to their proper Sovereign, the King of heaven.
To the evil of monarchy we have added that of hereditary succession; and as the first is a degradation and lessening of ourselves, so the second, claimed as a matter of right, is an insult and an imposition on posterity. For all men being originally equals, no one by birth could have a right to set up his own family in perpetual preference to all others for ever, and though himself might deserve some decent degree of honors of his cotemporaries, yet his descendants might be far too unworthy to inherit them. One of the strongest natural proofs of the folly of hereditary right in kings, is, that nature disapproves it, otherwise, she would not so frequently turn it into ridicule by giving mankind an ass for a lion.
Secondly, as no man at first could possess any other public honors than were bestowed upon him, so the givers of those honors could have no power to give away the right of posterity, and though they might say "We choose you for our head," they could not, without manifest injustice to their children, say "that your children and your children's children shall reign over ours for ever." Because such an unwise, unjust, unnatural compact might (perhaps) in the next succession put them under the government of a rogue or a fool. Most wise men, in their private sentiments, have ever treated hereditary right with contempt; yet it is one of those evils, which when once established is not easily removed; many submit from fear, others from superstition, and the more powerful part shares with the king the plunder of the rest."About one hundred and thirty years after this, they fell again into the same error. The hankering which the Jews had for the idolatrous customs of the Heathens, is something exceedingly unaccountable; but so it was, that laying hold of the misconduct of Samuel's two sons, who were entrusted with some secular concerns, they came in an abrupt and clamorous manner to Samuel, saying, Behold thou art old, and thy sons walk not in thy ways, now make us a king to judge us like all the other nations. And here we cannot but observe that their motives were bad, viz. that they might be like unto other nations, i. e. the Heathens, whereas their true glory laid in being as much unlike them as possible. But the thing displeased Samuel when they said, Give us a king to judge us; and Samuel prayed unto the Lord, and the Lord said unto Samuel, Hearken unto the voice of the people in all that they say unto thee, for they have not rejected thee, but they have rejected me, THAT I SHOULD NOT REIGN OVER THEM. According to all the works which they have done since the day that I brought them up out of Egypt, even unto this day; wherewith they have forsaken me and served other Gods; so do they also unto thee. Now therefore hearken unto their voice, howbeit, protest solemnly unto them and shew them the manner of the king that shall reign over them, i. e. not of any particular king, but the general manner of the kings of the earth, whom Israel was so eagerly copying after. And notwithstanding the great distance of time and difference of manners, the character is still in fashion. And Samuel told all the words of the Lord unto the people, that asked of him a king. And he said, This shall be the manner of the king that shall reign over you; he will take your sons and appoint them for himself, for his chariots, and to be his horsemen, and some shall run before his chariots (this description agrees with the present mode of impressing men) and he will appoint him captains over thousands and captains over fifties, and will set them to ear his ground and to read his harvest, and to make his instruments of war, and instruments of his chariots; and he will take your daughters to be confectionaries, and to be cooks and to be bakers (this describes the expence and luxury as well as the oppression of kings) and he will take your fields and your olive yards, even the best of them, and give them to his servants; and he will take the tenth of your feed, and of your vineyards, and give them to his officers and to his servants (by which we see that bribery, corruption, and favoritism are the standing vices of kings) and he will take the tenth of your men servants, and your maid servants, and your goodliest young men and your asses, and put them to his work; and he will take the tenth of your sheep, and ye shall be his servants, and ye shall cry out in that day because of your king which ye shall have chosen, AND THE LORD WILL NOT HEAR YOU IN THAT DAY. This accounts for the continuation of monarchy; neither do the characters of the few good kings which have lived since, either sanctify the title, or blot out the sinfulness of the origin; the high encomium given of David takes no notice of him officially as a king, but only as a man after God's own heart. Nevertheless the People refused to obey the voice of Samuel, and they said, Nay, but we will have a king over us, that we may be like all the nations, and that our king may judge us, and go out before us, and fight our battles. Samuel continued to reason with them, but to no purpose; he set before them their ingratitude, but all would not avail; and seeing them fully bent on their folly, he cried out, I will call unto the Lord, and he shall send thunder and rain (which then was a punishment, being in the time of wheat harvest) that ye may perceive and see that your wickedness is great which ye have done in the sight of the Lord, IN ASKING YOU A KING. So Samuel called unto the Lord, and the Lord sent thunder and rain that day, and all the people greatly feared the Lord and Samuel. And all the people said unto Samuel, Pray for thy servants unto the Lord thy God that we die not, for WE HAVE ADDED UNTO OUR SINS THIS EVIL, TO ASK A KING. These portions of scripture are direct and positive. They admit of no equivocal construction. That the Almighty hath here entered his protest against monarchical government is true, or the scripture is false. And a man hath good reason to believe that there is as much of king-craft, as priest-craft, in withholding the scripture from the public in Popish countries. For monarchy in every instance is the Popery of government.