Oddly enough I have always thought that Charles was overly influenced by his trip to Spain seeking the hand of the Infanta Maria.
I think he saw the possibilities of an absolute monarchy in Philip III's court and it gave him ideas about his reign.
Had he not gone to Spain he would not have the influences (and he and his father would have been more popular in England) of "foreign" courts.
Another possibility would be that Charles married a Protestant, I don't know if the Dukes of Prussia had any daughters available but if so this would be a useful choice.