Common principles of communication are relevant to this topic. Still, you and your Missions Team must be the judge of effectiveness for your congregation. If your church responds best to oral announcements, then by all means use oral announcements. On the other hand, if it is really important, you should plan to use multiple channels of communication: personal, oral, audio, video, email, print media.
Effectiveness generally falls along the spectrum of personal and direct vs. impersonal and indirect, e.g. –
Personal telephone call
Personalized snail mail
Announcement or insert in the Sunday bulletin
Print posters or bulletin boards
Video clip features
The most effective is always the direct, face-to-face appeal. Timing is significant also. Your event promotion should begin ASAP, well before the event but after prior calendar priorities. If your missions celebration occurs with predictable regularity, people will be able to anticipate the scheduled event. A variety of means and media will increase your audience reception and response.
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