Doctrine. What in the world does this word even mean? It's actually quite simple-it means teaching. But when was the last time you heard a teacher say "We will now study the doctrine of math"? Its a word which is highly alien outside of Christian circles and typically frowned at even within since "doctrinal" sermons have historically been characterized by the nouns boring, irrelevant, and dogmatic. Since doctrine is simply the teaching of the Bible - a teaching which tells a story about God - I prefer to use the phrase "God-story" instead.
Brothers and Sisters. Seriously, no one goes around in every day life calling people brother or sister. The closest I have come to this is in certain African American settings where it is cultural for them to call each other brother or sister. If that's your context then by all means have at it. But whenever I hear "brothers and sisters" from the pulpit I automatically think the speaker is out of touch. I often just use the word "guys" instead since that's how I talk in every day life.
Peculiar. So we are supposed to be a peculiar people. I get it. But how about we communicate that message by using a less peculiar word? Seriously, whenever I hear someone use this word my mind automatically conjures up images of people living in the 1800's. It's simply an old word, seldom used except maybe in poetry, and even has a boring sound to it. I prefer to use words like unique, counter-cultural, unusual, or even rebellious.
Beloved. OK everyone, Shakespeare lived and died a long time ago. No one says beloved anymore, its a relic of the past, so maybe calling the people in the audience "beloved" should be a relic of the past as well. Seriously, unless your entire audience is stuck in the 1800's this one should definitely go. As in "brothers and sisters" I have replaced this one with a simple "guys".
Revival & Reformation. Whenever I hear these terms I think of long faced rigid Christians who have no desire other than to make the entire Christian church as rigid as themselves. Of course, this is not what the terms mean but because so many have misused them in the past this is the connotation that they have come to have. In addition, the terms - especially the word "reformation" - are outdated. Reformation was a popular word in the 1800's and was being used all over the culture in the realm of social action but today the term is seldom used. I prefer to use the terms "reclaim, reboot, revolution, or restore".
Other examples include words and phrases such as: end times, last days, reverence, born again, slave to sin, fellowship, altar call, pulpit, benediction, call to worship, vespers, main service/ worship service, amen etc. All of these are words which are highly irrelevant to both younger and secular audiences and if we use them flippantly, without taking into consideration the linguistic gap we are creating and fostering by refusing to update our terms, we alienate people that we are meant to be serving.
Now of course, we can't always replace the word and neither should we feel that we need to, but at the very least we should explain the words with modern illustrations so that the audience learns what it means. I do, however, recommend replacing the outmoded ones entirely as they present a barrier of understanding to those who speak a different generational language. In my own life I have discovered how easily truth is received when the right words to convey it are used. Instead of trying to be so fancy and religious all the time let's bend over backwards to make truth simple and accessible to those who don't share our church-culture.