Methodism's rise from a small coterie of religious societies at Oxford University in the 1730s to a major world communion by the beginning of the twentieth century, followed by its relatively sharp decline in the late twentieth and twenty-first centuries is a complicated story. Methodism crossed boundaries of nationality, ethnicity, gender, race, social class, and culture. Its political activism ranges from John Wesley’s support for King George III during the American Revolution to the church’s recent opposition to the Vietnam War and the Iraq War. Feminist scholars are undecided as to effect of Methodism on the women's liberation movement. African-American Methodists are both proud of their denomination's early opposition to slavery and ashamed of its later capitulations.
Over the years Methodism has tended to thrive on opposition and competition from other denominations.
In Methodism: Empire of the Spirit, David Hempton, former Dean of Harvard Divinity School, describes the rise and fall of Methodism in extreme detail. Methodism is not a product of the Protestant Reformation, but rather, an offshoot of Anglicanism and, as such, it expanded into areas where Anglicans and other English speakers migrated.
A key reason for the rapid advance of Methodism was its willingness to adapt to its environment, to include the customs and traditions each new location. Likewise, a reason for the recent decline in Methodism might be its failure to keep up with certain cultural changes. I am not sure how Dr. Hempton would explain the membership increase in evangelical denominations during this recent period.
Overall, after reading the entire book, I found it presented far too much detail and was a rather difficult read. However, it is an excellent source of information and the knowledge gained was probably worth the drudgery. As a reference, this book is fine, but if you plan to read it, bring a lot of patience.