'True God' in the Bible

Among our hearers was one named Lydia, a dealer in purple goods. She belonged to the city of Thyateira, and was a worshipper of the true God. The Lord opened her heart, so that she gave attention to what Paul was saying.

So he left the place and went to the house of a person called Titius Justus, a worshipper of the true God. His house was next door to the synagogue.