I'm Catholicism, no form of contraception is OK as Catholics believe that life starts at conception, ie as soon as the sperm enters the ovum. The most acceptable form of preventing pregnancy is the rhythm method. In Catholicism sex is not done for fun, it is purely for procreation, they were instructed to 'go forth and multiply'. I'm sure that for all Christians it is the same but I had a Catholic education so that's the denomination I'm certain about.
Obviously though, Christians are no longer having 14 children like my great grandparents generation did so they are using contraception nowadays, as Grace's family must be doing, there's only 3 Booth children, after all
In my Catholic education in the 90s, we were told that the rhythm method was the only acceptable method. Obviously, we weren't told what the rhythm method was, only that the pope approved of it