It sounds like that the nature of the prompt is a narrative one. It is asking you to describe your experiences with encountering someone who is religious. If you really wanted to make this assignment worthwhile, I would arrange an individual appointment with someone who has devoted their life to religious service. Conducting an interview or discussion with a priest, rabbi, cleric, or someone of this capacity would be an excellent starting point here. Asking them questions about what they consider to be the meaning of life, the purpose of existence, why suffering is present in the world, how does one navigate through the field of sin, and/ or how we know God, as a force, exists could reveal some really powerful answers. Being able to ask someone who is a religious servant these questions could make for a great writing task and could also open new doors of perception in your own life. It would really be a sight to behold if you were able to conduct separate interviews with religious people from different faiths and backgrounds and compare these points of view. If you approach this in the right way, this assignment could be more than a grade, more than a writing task. It could actually be one of those endeavors that could change your life or alter your thought process about being in the world.
You could write about the encounter with any religious person . My suggestion would write about an encounter with Mahatma Ghandi . You could write about spending a day with him and learning about his inovative way of living and you could write about some of the quotes that he said and pretend that he was saying them too you and giving you advice.