What is the most likely reason that most members of Congress passed this resolution?

Without knowing which resolution you are referring to, I cannot provide a specific answer. However, in general, members of Congress pass resolutions for a variety of reasons, including to express support or opposition for a particular issue, to recognize or honor individuals or groups, or to establish rules or procedures for the functioning of Congress. The most likely reason for passing a resolution would depend on the specific content and context of the resolution in question.