At the time the great European powers were all in a race to take the most land (and Britain won). Britain also had the best navy and could project power. Britain won some wars against European nations and took their colonies. During that time the "United Kingdom" for formed. And Company Raj (Company Rule) with the East India Company in India made Britain more and more wealthy. After all, if you control much of the world you can get very rich and control much of the trade. Britain also had a lot of Soft Power in addition to its hard power (the military).
In addition to the previous answer, Britain is also one of the first country to consolidate power and create a strong monarchy. They defeated the Spanish Armada and became the best Navy of the time. During the age of exploration, they took colonies all over the world. Thus the statement "the sun never set on the British empire". The American colonies help them become a global power by trading raw materials. Britain were the first to go through industrialization and urbanization. Not much religious conflict.
