Sažetak There is considerable confusion present in the Evangelical world when it comes to defining ecumenism. There is no common definition, strategy or goal, unlike in the Roman Catholic Church, which has clearly defined its terms, goals and the main goal of ecumenism in the Second Vatican Council, in the Pope’s encyclicals, as well as some other documents. Even though ecumenism has spread beyond the circle in which it was started, outside of Protestant-Evangelical Christianity, and today includes the Roman Catholic and Eastern Orthodox Churches, and even Islam, I will attempt to answer
the question in the title by considering the relationship between Evangelical Christianity and the Roman Catholic Church, which has taken a leading role in the ecumenical movement after the Second Vatican Council. In the first section, I will consider the historical emergence of ecumenism in churches which stemmed from the Reformation tradition; I will define the non-biblical term of ecumenism from a biblical standpoint; I will answer the question “why YES to biblical ecumenism”, and I will go on to review some arguments
as to “why NO” to the different, expanded ecumenism, i.e. I will answer the question of where the boundaries are, or, what are the specific obstacles for ecumenism outside certain boundaries.