In the early years of Christianity, the Neoplatonic philosopher Porphyry emerged as one of the major critics with his book Against the Christians. Porphyry argued that Christianity was based on false prophecies that had not yet materialized. Following the adoption of Christianity under the Roman Empire, dissenting religious voices were gradually suppressed by both governments and ecclesiastical authorities. A millennium later, the Protestant Reformation led to a fundamental split in European Christianity and rekindled critical voices about the Christian faith, both internally and externally. With the Scientific Revolution and the Age of Enlightenment, Christianity experienced additional attacks from major thinkers and philosophers, such as Voltaire, David Hume, Thomas Paine, and the Baron d'Holbach. The central theme of these critiques negated the historical accuracy of the Christian Bible and focused on the perceived corruption of Christian religious authorities. Other thinkers, like Immanuel Kant, launched the first systematic and comprehensive assaults against Christian theology by attempting to refute arguments for theism.
In modern times, Christianity has faced substantial criticism from a wide array of political movements and ideologies. In the late eighteenth century, the French Revolution saw a number of politicians and philosophers criticizing traditional Christian doctrines, precipitating a wave of secularism in which hundreds of churches were closed down and thousands of priests were deported. Following the French Revolution, prominent philosophers of liberalism and communism, such as John Stuart Mill and Karl Marx, criticized Christian doctrine on the grounds that it was conservative and anti-democratic. Friedrich Nietzsche claimed that Christianity fostered a kind of slave morality that suppressed the desires contained in the human will. The Russian Revolution, the Chinese Revolution, and several other modern revolutionary movements have also led to the criticism of Christian ideas.
The formal response of Christians to such criticisms is described as Christian apologetics. Philosophers like Augustine of Hippo and Thomas Aquinas have been some of the most prominent defenders of the Christian religion since its foundation.
Biblical criticism, in particular higher criticism, covers a variety of methods used since the Enlightenment in the early 18th century as scholars began to apply to biblical documents the same methods and perspectives which had already been applied to other literary and philosophical texts. It is an umbrella term covering various techniques used mainly by mainline and liberal Christian theologians to study the meaning of biblical passages. It uses general historical principles, and is based primarily on reason rather than revelation or faith. There are four primary types of biblical criticism:
Within the abundance of biblical manuscripts exist a number of textual variants. The vast majority of these textual variants are the inconsequential misspelling of words, word order variations and the mistranscription of abbreviations. Text critics such as Bart D. Ehrman have proposed that some of these textual variants and interpolations were theologically motivated. Ehrman's conclusions and textual variant choices have been challenged by reviewers, including Daniel B. Wallace, Craig Blomberg and Thomas Howe.