The root of "logo" in Greek means to speak, say or tell. That is the purpose of your church logo; to tell others about you through a simple image. Logos are a representation or emblem that identifies your church to your community and because they are an identifier, serious thought needs to be applied before you just pick one. It will become your stamp or image to your community and your church so it should, as clearly as possible, make a statement about who you are and where you are going.
Your church logo should become a part of everything you do. It should not necessarily be overbearing in design, but must be included. The logo should become so much of a statement about who you are that if you were to carry a banner with your logo in a local parade, people five blocks away would know who is coming up the street.
With all that being said and understanding the importance of the logo, how many does a church need? This question has multiple answers so bear with me as I try to help you sort this out.
1. You need one logo. That was simple, I can quit reading right? Not quite yet. Not to restate the introduction, but having a strong logo is important and there should be one for the church as a whole. It is the umbrella that covers all of the church activities and ministries. It should be seen the most in almost all circumstances.
2. You need additional logos depending on "who" you are communicating with. As you look at your church and outreach, you need to look at various ministries broken down by age, possibly gender and other demographics. For instance a youth ministry will have a target demographic a bit different than a quilting bee. As the goal is to communicate effectively a logo should be developed to speak to that group. That does not mean that every class or ministry needs a logo. However, if there are demographics that need to be spoken to in a different way then a logo can be developed for each. Keep in mind that just as much effort needs to be put into each of these logos as the main church logo. Common logos based upon the "who" include: Children Ministries, Youth Ministry (Middle School and High School), Senior Ministry Teams (Senior Saints), Women or Men's Bible Studies.
3. You need a logo for "what" you are doing. Most often the church logo will do for most special efforts. However, you need to think more broadly if you are partnering with a non-church group or other ministries. A school supply give-a-way may need a special logo. Also, many internal programs and projects probably need to be set apart with a special logo. Common logos based on "what" include: new believer classes, building projects, and some sermon series.
4. You need different logo if you are building a new or different brand. For instance planting a new church or starting a church within a church may need a new logo to communicate to their target. Think of Pepsico. They have one logo for Pepsi, but a totally different set of logos for their other sodas like 7Up and even more for their food brands like Fritolay or Quaker Oats. A different brand even in the same company requires a different logo.
The bottom line is to think through your logo needs and approach the logo creation in a thoughtful careful way. The place to start is with a solid church logo that says what you want it to say. From there branch off to the others keeping your general theme along the way. Rely heavily on your vision and mission statement for guidance for your theme and think about who you are trying to talk to. Don't be afraid to rethink your logo as an update is warranted every five to ten years. With all of this in mind you should be able to create a communication device that will help your church speak to the congregation and the community. Lastly, don't be afraid to ask for help from a professional, just be clear about cost and logo ownership up front.