Complex sentence: Catholics tended to keep to themselves in their own section of each town, even though they were one of the largest single denominations: for example, the Catholic painter Johannes Vermeer lived in the "Papist corner" of the town of Delft.
Split into simpler sentences: Catholics tended to keep to themselves in their own section of each town, even thought they were one of the largest single denominations. For example, the Catholic painter Johannes Vermeer lived in the "Papist corner" of the town of Delft.