The doxology is the last line of the Lord’s Prayer, “For thine is the kingdom, the power, and the glory forever and ever. Amen.” It is, to be more precise, an ancient prayer traditionally added on to the Lord’s Prayer (as found in Matthew, normally), and a version of it dates back to the beginning of the 2^nd century – meaning some Catholics, at least, were praying it this way more than 1300 years before it became “the Protestant version”. Or one might just say it is one other way in which Catholic tradition has been kept better outside the Catholic communion. In any case…

The reason Catholics have become used to the Our Father without the doxology is liturgical – when we pray the Lord’s Prayer during the Eucharistic liturgy, we pause between the end of the Prayer proper and the doxology to allow the priests’ embolism, “Deliver us Lord, from every evil…” Even though we pray the doxology every Sunday, we are habituated to stopping after “…deliver us from evil”, such that when we are taken out of the Sunday liturgy, we continue to stop.

In fact, however, the embolism is only part of the Eucharist, and is not part of other liturgies, such as the Liturgy of the Hours. In those times, we should pray the entire prayer, with the doxology, even when it is not an ecumenical prayer service. If we do this regularly, it will seem less uncomfortable when we do get to a mixed liturgical setting, and be better hosts to the other Christians who rarely omit this last line of the prayer.