Just a quick note here John then I'll stick my credo-baptist nose elsewhere:
Quote
And on the Sabbath day we went outside the gate to a riverside, where we were supposing that there would be a place of prayer; and we sat down and began speaking to the women who had assembled. A woman named Lydia, from the city of Thyatira, a seller of purple fabrics, a worshiper of God, was listening; and the Lord opened her heart to respond to the things spoken by Paul. And when she and her household had been baptized, she urged us, saying, "If you have judged me to be faithful to the Lord, come into my house and stay." And she prevailed upon us.
Acts 16:13-14 NASB

Because it is A. The Sabbath and B. Lydia was worshiper of God.

She probably fell under the category of being a God Fearer Having some knowledge of the religion of Israel.

Carry on.

Peter

If you believe what you like in the gospels, and reject what you don't like, it is not the gospel you believe, but yourself. Augustine of Hippo