We have reached the great story in Acts where Paul and Silas are jailed, and at midnight there was a great earthquake and the prisoners were set free but did not run away. The jailer was so amazed that he asked what did he have to do to be saved. The instruction:
Believe in the Lord Jesus and will be saved.” So they spoke the word of the Lord to him and to everyone in his house. He took them in at that hour of the night and bathed their wounds; then he and all his family were baptized at once.
Notice it says he and all his family. Actually the word used in the passage is oikos. It refers to a house, and therefore the household. It would have included not just the adults but chidlren, and even slaves if there were any. Infant baptism was a part of Christianity from the beginning.
While there is some history of individual conversions in early Christianity, the more common practice was for households to become Christian. Often enough it was the father, and as he went so the entire household, as in the story of the jailer. Parents didn't asks their children what religion they wanted to be, or wait and let them make up their mind. They led the family of faith.
Since the time of the scriptures we have referred to the family as the domestic church. This is really a continuation from Judaism, after the destruction of the temple, where the home is the center of worship.
The whole family including the infants would be baptized and the parents would lead their children in prayer. Many ethnic groups over the centuries would set up small "altars" in their homes with crucifixes and other images that served as visual reminders of the faith, and the great examples of the saints.
Perhaps this reading is a reminder to all of us to look around the house. If someone came in, would they know that it is a Christian home. When was the last time you came together as a domestic church and prayed. Oikos is not just a brand of yogurt. The word reminds us that all those who live under the same roof should be united, above all in prayer.