# Neither should they pay attention

"And I also want you to command them not to pay attention"

# to stories

These may have been stories about their ancestors.

# endless genealogies

With the word "endless", Paul uses this to emphasize that the genealogies are very long. "Genealogies" refer to the written or verbal record of a person's parents and ancestors

# These promote arguments

"These make people angrily disagree." 

# rather than the plan of God, which is by faith

"rather than helping people to understand God's plan to save us, which we learn by faith" or "rather than helping us to do God's work, which we do by faith."