They’re mostly within the neo-Pentecostal movements, especially in the Global South. The very un-Christ-like reasons why:
Although these movements have some roots in the Pentecostalism that emerged in California in the early-twentieth century, as well as in the charismatic revivals of the 1960s and 1970s, the neo-Pentecostal churches are notable for their emphasis on a single charismatic leader and the witnessing of miraculous signs, and for teaching a strong version of the “prosperity Gospel” (the belief that financial success is the result of divine blessing).
Sociologists studying the movement – preeminently David Martin – suggest that the popularity of these churches is related to the way in which Christianity is linked to access to power. People are drawn to the neo-Pentecostal movement because they believe that their participation will result in some tangible results: financial success, health, successful marriage and so on. It is perhaps thus unsurprising that, generally speaking, individuals in less developed countries, particularly those making the transition from rural areas to large urban centers, are most likely to attend neo-Pentecostal churches.