Whether or not missionaries dress up for Halloween is at the discretion of their mission president. Missionaries are not allowed to proselyte in costume and their appeal is to reflect the Church's guidelines for missionary clothing.
To some, choosing a Halloween costume can be a thoughtful process.
For these missionaries, choosing a Halloween costume was a creative extension of their missionary work.
On their Facebook page, Mormon Memes shared this picture of Elder Jensen and Elder Wegelen at a ward trunk-or-treat party dressed as the Book of Mormon and the Holy Bible.
But they are not the only ones to do so.
Cassi Franks, a commenter on Mormon Meme's post, also shared a picture of missionaries dressed as the Old Testament, New Testament, the Book of Mormon, and the Doctrine and Covenants combined with The Pearl of Great Price at a trunk-or-treat party.
But these costumes are not only creative, they also share a little bit of what Church members believe in a festive but mission-appropriate way.