Originally Posted by R Harris

The difficulty with the household baptisms in Acts 16 (Lydia and the Jailer) is that Luke provides us with no information regarding the other members of the household, regarding age, sex, or whether they made a profession or not.

Lydia believes, and is baptized along with her household. The Jailer believes, and is baptized along with his household. Luke makes no mention whether the other members of the household made a "valid" profession of faith. So, the credo-baptist must make an inference/assumption here.

But for the covenantal baptist, who believes that baptism has replaced circumcision as the sign and seal of the covenant (cf. Colossians 2:11), and that we see corresponding household circumcisions in the OT (Genesis 17), this is the natural occurrence that we would expect to see.

Speaking of adults not believing but still being baptized, we do see that clear example of Abraham's servants being circumcised, but we get no hint whatsoever that they had the faith that Abraham had (Genesis 17; Romans 4:11). So the issue is not just with 8 day old Isaac and infant circumcision/ baptism; the matter does indeed affect the entire household, with servants included. Even reformed paedobaptists often miss this point, which leads to the confusion and difficulty of the discussion.