The number of people killed by the Inquisition (by which people largely mean the Spanish Inquisition) is variously estimated to be anything from 30,000 to 50 million. The actual number is likely to be nearer 3,000 over 300 years. This is not to justify or excuse what was an appalling chapter in one aspect of the church’s history – but it does set it in context. And as Jack shows in his answer below – the Inquisition had nothing to do with the spread of Christianity. Feel free to respond with your comments – or indeed follow up questions.