I have done a good deal of college and community theater. The term "willing suspension of disbelief" usually refers to the audience. As an audience member, I have to be willing to forget that I am seeing only actors delivering memorized lines, and that what is happening is not real.
So I am not sure exactly what your question means, but I think I have something to say about it anyway! 😂
In my experience, there are different kinds of atheists and different kinds of believers. There are atheists who have a great deal of respect for religious people and for the experience of "having faith", even though they disagree. And there are atheists who are cynical and antagonistic toward anything smacking of religion.
Likewise, there are religious people who have experienced that doubt is a part of faith. There are religious people who have known and respected atheists who are good and even admirable people. On the other hand, there are religious people who will dismiss out of hand anyone who does not believe as they do.
Those distinctions not only apply to the actors who might appear in a play, but they also apply to the characters being portrayed.
And there are atheists who used to be believers, and believers who used to be atheists, so actors of either type can draw on past life experience.
So I will boldly and decisively answer your question with "it depends." 😌
