Also pack a spillproof cup of water. Sit very close or way in the back. This works differently for different kids. Promise an after-church treat on occasion for good behavior. Look into church babysitting co-ops by parents during the service.
Some churches have classes for preschoolers during the worship service.
Be sensitive to your kids' developmental stages. Some kids need to stay home until they're in preschool. Others do well at eighteen months. Nancy R. Scappoose, Oregon Your problem may be your church. Our church makes it clear that children are welcome.