I went on a health service mission with a group to Honduras (where I actually served my LDS mission).
We went to visit some sick people. I thought it was weird that the guy I was with, as we were talking to an old catholic lady, kept telling her that she needed to accept Jesus and become Christian.
I gathered that believing in Christ doesn’t make you Christian in their eyes. It is being a part of their church.
I disagreed with his viewpoint, didn’t bring it up. Somehow the guy I was with didn’t think the lady had accepted Christ, despite her wearing a cross and expressing belief in him.