Our church doesn't specifically design the service with children in mind and leaves it up to the parents whether or not their kids stay for the sermon (4 yrs and up all come to the music portion then 4 yrs to 3rd grade can go to children's church during the sermon.) However, our church is very welcoming to all children who are in our services. (A little secret, I love, love, love hearing the sounds of children in the worship service. This has not always been true for me, but now, it's one of my favorite things.)
One of the things each church must decide, once they decide to welcome children into the service, is whether or not to gear the service toward children. I don't feel like you need to tailor the service to children, but train and give parents tools to help them lead their children during worship (worship through music and worship through the preaching of the Word.) The following are some examples, just based on the trial and error of the last 5 years with my two children (one girl and one boy who couldn't be more different from each other in how they respond to and participate in the service):
Music: If you think your child doesn't know or understand the song, explain it to them while you sing. More than likely, if you are doing any kind of family worship or devotion at home, there will be words in the songs that are familiar to them. When one of those words comes up, you turn to them quietly and say, "We're singing about the cross (or whatever word or words are familiar.) Who died on the cross?" This may lead to other questions from them, but even if it doesn't, you've reinforced something you want them to know. When my son was learning to read he would get so excited when he saw a word in the song he could actually read. Those are also little teaching moments when you can read more words to them or ask them if they know what those words mean. The bonus of doing this is that it makes you think much more about the words that you are singing and the meaning of each song. It's good for you and your children.
Prepare them for what's about to happen:Go over the order of service with your child before the service starts (which would also allow a time to explain songs or even read the scriptures ahead of time.) My son always wants to know how close we are to being done (yeah, he's not real spiritual, yet), so it helps when I walk him through the order of service and let him mark off each thing as we do it. He sees where we are and that ends his constantly asking me, "Are we almost done?"
When your child isn't the one with their hands raised, eyes closed, singing: It's OK if your child isn't worshiping (especially if they aren't saved) or worshiping just like you (my son DOES NOT like to sing and refuses to do so in church. It seems to me that he's tuned out, but when he gets home he's humming the songs we were singing and it gives us another chance to talk about them.) I do my best to get him to at least stand with us, as a sign of respect for God and for those leading us in worship, but some weeks that is a fight not worth having. At one point, I made egg shakers (plastic Easter eggs filled with rice and taped closed-just tape them VERY WELL) they could use each week during the music. My daughter absolutely loved it every week and, honestly, it really even added to my worship to hear her playing along to the songs. My son liked it for awhile, but he prefers to use a pen on the back of the seat in front of him to drum. I say, whatever works to keep their attention and help them see they are part of worship, too. Not every adult in your service worships the same way, so why should the kids?
But they are so squirmy: It's OK not to expect them to sit perfectly still (in my opinion, they aren't coming to worship to learn how to sit still. They practice every day at school.They are there to experience what it's like to gather as a church family, to learn from God's word, and to join in corporate worship) and some kids need something in their hands to focus (that would be Ethan.) Don't be frustrated if you feel they aren't paying attention because they are squirming or moving around. You may be surprised if you ask them questions about the sermon and music on the way home and they can answer every one. Just because they are drawing or using their pens as rocket ships doesn’t mean they are tuned out.
Prepare them by reading the Bible with them at home and participating in other programs at church: My kids get so excited when they hear a Family Quest verse (our church’s Wednesday night family Bible study program. It's amazing! I'd love to tell you more about it if you are interested) or a verse we read during devotions in the sermon. For that to happen, it means parents have to be pouring God's word into them at home. This doesn't have to be terribly time consuming, but it does have to be a priority. There are all kinds of children's Bibles, devotional Bibles, and family Bibles that have reading plans and pretty much do all the work for you. Grab one and get started. That's what it takes, friends. Just.get.started. Even reading one chapter or a few verses a day is laying a foundation for your children. The Bible promises that His word will not return void, so get as much of the Word in them as you can.
Talk to your pastor: Ask the pastor ahead of time what his sermon title and scripture are so you can be reading and talking about it with your kids during the week. I have done this a lot with my pastor and he was very generous to give me what I was asking for each time. For awhile, I was even making a worship notebook for each child, each week, based on what the pastor gave me. I included coloring pages on the topic, words to listen for (be careful when you ask the pastor for a word he will use frequently because he may give you a word that he will say in every sentence and your child may be so excited to hear the word he's looking for that he squeals loudly with delight and repeats the word every time he hears it. Not that that's happened to me or anything...), a generic page for taking notes, and a spot to write or draw about what they remember from the service. Admittedly, this is a lot of work to do each week. It was truly something I enjoyed for about a year, then life took over, and it became too much for me. You can find many of these types of pages for free online and even some bound books that do basically the same thing on Amazon.
Don't be frustrated that they don't understand everything that is said: God's word will not return void. If they hear it, He'll use it. Lord willing, they won't hear that concept or theology just that one time, so if they don't "get it" after one sermon (how many adults do???), it's OK. You're building foundation. You can continue to follow up at home. Because we homeschool, our kids get the Bible on their level in school, Family Quest, and Sunday School, so I think it's good for them to hear it on another level once a week. Do they always enjoy it? No. Do they hate me for it, time will tell. But, testimonies take time and change rarely happens overnight (I have to remind myself of that often.) I have always found that when I take the time to answer their questions and point things out to them I learn more than when I am just taking notes. It forces me to pay attention and dig into the word to be able to find the answers they seek. Trust me, it is possible to answer their questions and not totally disrupt the service. (Sometimes the people around you even learn something, too!)
I hope this was helpful and encourages you to give taking your children with you to worship a try, even if it's just once a month for awhile. Check out these links for some great resources that I have enjoyed over the years: