Kathy asks if a fifth grader who did not earn the Webelos badge can earn the Arrow of Light. Yes he can. The Webelos badge is not required for the Arrow of Light.
Webelos Adventure: Duty to God and You
Duty to God and You is one of the Webelos CORE Adventure Requirements. For this adventure, Webelos either earn the religious emblem of their faith or plan and take part in a worship service or reflection.
Printable helps for requirements:
Two Cub Scout leaders ask about how to complete the faith related requirements with Cub Scouts who are raised in agnostic homes.