The first Christians were all Jewish. What's more, in those early years they faithfully followed Jewish practices. The Eucharist, for example, was something they did in addition to the Sabbath rituals.
Gradually, however, they found themselves as odds with some of the Jewish leaders and were told that belief in Jesus as Messiah and Lord excluded them from the synagogue. (Paul, before his conversion, is an example of those who persecuted early Christians.)
Over the course of 20 centuries, Christians have been persecuted from time to time ... and Christians have also done their share of persecuting.
But the Second Vatican Council explicitly taught respect for those of other faiths, including those of non-Christian faiths.
True ecumenism's first goal is to find areas of understanding and agreement, and to treat differences in light of those common areas.
Your time with the Lord today might best be spent praying for unity among Christians.
- Little White Book, Diocese of Saginaw