Lamoni must have been simultaneously reassured but also confused. Had Ammon been a god, then Lamoni could easily explain his feats of strength and perception. But those feats surpass mere mortal ability. Lamoni’s sincerity is evidenced by his offer to give Ammon anything he wants in exchange for that information. Lamoni’s motivation is unknown, but I speculate that Lamoni was wondering if there was some way that he himself could command similar powers.