Atlantic pirates of the 17th to 19th century were, for the most part, Christian. Although obviously not too observant of the 8th Commandment.... thou shalt not steal.
There are several reports of new pirates being sworn in on Bibles. Pirates were also known to shuttle missionaries around to far off remote places.
While the primary goal of pirates and privateers was financial gain, religious zeal also played a vital role in pirate attacks. English, Dutch and French Privateers were employed to champion the Protestant faith against Spain, defender of Catholicism.
Sir Francis Drake was known as Queen Elizabeth I’s Pirate. Drake was one of many privateers who zealously protected “God, Queen, and Country.” Drake was knighted for his efforts in attacking the Spanish in the name of religion.
Bartholomew Roberts (aka Black Bart) adhered to his own Christian standards wearing a diamond cross around his neck. He reserved Sundays for rest, banning his crew from working on that day. Bart did not drink alcohol, only tea, and did not allow alcohol or gambling onboard his ships. This strict adherence to his beliefs possibly led to him being called the most successful of the famous pirates, taking 400-500 ships in 2 years, 6 months.
In William Kidd's case, the role of religion in a pirate's life often only emerged while awaiting death. Pirates were frequently visited by priests, who encouraged them to repent, before their hanging.
Kidd, convinced of his innocence, ignored the priest's pleas for repentance. During his hanging the rope broke. While lying on the ground a priest convinced him that this had been the work of God. Then, Kidd declared openly that he repented.