What were the main ideas of Voltaire on religion, government, and so on? What were the major ideas he criticized or believed?
Voltaire was very much a leading figure of the Enlightenment and as such embodied that movement's myriad contradictions. As regards religion, he was profoundly hostile to the power of the Catholic Church, which he saw as perpetuating ignorance, superstition, and obscurantism. He was especially hostile towards the Church for its perceived antipathy towards developments in natural science.
Nevertheless, Voltaire was not an atheist. He once famously stated that if you abolished God it'd be necessary to re-invent him. This illustrates an attitude widely shared among the philosophes. Religion still had its place, but only as a means to provide the illiterate lower orders with moral instruction so that they wouldn't get any bright ideas about wanting equality or, say, challenging the property rights of wealthy bourgeois such as Voltaire.
In common with a number of other Enlightened thinkers, Voltaire was a deist. Simply (and somewhat crudely) put, this is religion for intellectuals. God exists, but he no longer intervenes in his creation. He sets the whole thing going like a gigantic watch and sits back and lets the laws of nature do their thing without any need for him to get involved. So there are no acts of God, no miracles, and no point whatsoever in prayer. God is simply the necessary first stage in a scientific and philosophical hypothesis, and that's pretty much it.
Voltaire was also an unabashed elitist who regarded the mass of humanity as being ignorant, foolish, and, worst of all, unenlightened. Government was needed, therefore, to keep their passions in check and prevent the body politic from being infected with the virus of unreason. His political philosophy was that of "enlightened despotism." What mattered was not the form of government, but whether it was geared towards rational ends. If it required a despot such as Frederick the Great or Empress Catherine of Russia to achieve these ends, then so be it.
Voltaire (1694-1778) was a French philosopher, poet, historian, and playwright. He opposed authority and tradition, specifically the authority and tradition of the French government and the Catholic Church.
He was a large supporter of civil rights, especially freedom of speech and freedom of religion. Many of his famous works openly criticised the French government and the Catholic Church, which resulted in his exile to England in 1726 and again in 1734.
Voltaire largely distrusted democracy because he viewed it as an "idiocy of the masses." He also believed that an enlightened monarch needed to keep in mind the best interests (power and wealth) of his subjects in order to make meaningful governmental changes.
In terms of religion, Voltaire believed the bible was outdated and metaphorical, rather than a divine gift from God. He was a deist, which is a person who believes in the existence of God, but who does not believe that God intervenes in human life or the universe. He was very unpopular with the Catholic Church because of these beliefs.
Voltaire did not believe in any single religion, and did not believe that one was needed to believe in God. Instead, he was very much interested in the natural laws that were underlying in all religions. Voltaire, like most Enlightenment thinkers, considered himself a deist.
Voltaire supported tolerance towards religions and ethnicities, both. He was opposed to slavery and wrote about it in some of his book, discussing “the price we pay for sugar in Europe.” He was however cited on several occasions for being anti-Semitic.
Voltaire distrusted democracy as too unpredictable and believed that only an enlightened monarch could bring about change. He hoped that such a person would improve both the health and education of his subject.