Sound inference depends on a valid relationship between premises, and sometimes on their appropriate arrangement. Seemingly relevant statements can fail to establish a conclusion if the necessary middle connection is missing.
Valid pattern: Every established messenger truthfully conveys the divine message; this person has been established as a messenger; therefore his authenticated religious message is true.
Invalid leap: This person is generally honest; honest people are admirable; therefore everything attributed to him is certainly revelation.
Ordinary honesty does not itself establish divine commission. This is why prophetic authority requires its own proof.