Contact your local home-school organization. It can put you in contact with other parents who home-school their children through a Christian program. Once you can get in touch with these people, set up a playgroup so the children can meet one another.
Enroll your children in community sports or other activities. Find an outlet for your children in which they can socialize and exert some energy after being home for most of the day.
Invite younger family members over once a week. While helping a Christian home-school child socialize with peers is very important, it's wonderful to have the children engage in quality family time with their cousins as well.
Ask your child if he wants to volunteer at a local center. Many families bring their children to homeless shelters, elderly housing, or hospitals where they can learn to help others. This is an wonderful opportunity for socializing.
Encourage your child to meet new neighborhood friends. Coordinate playgroups with other mothers one the block once or twice a week.