Has a religion ever been completely converted into a new one?
All religion has been modified and shaped into something different by whatever preceded it....remember religion started out as simple rituals,then exploring,then the spread of religious ideas started.
lots have, just remember the pope lives in Italy
Most religions are spin-offs of others.And the Pope lives in the Vatican,in Italy.
All religions are converted from previous religions.Christianity is a combination of Mithraism, Egyptian mythology, Essene/Nazarene communities, politics that evolved into what it is today.