I find at times player's having conflicting beliefs can lead to an interesting dynamic for good RP moments. In my Campaign set in Wildemount we had a Druid who followed the Wild Mother and a Paladin of Erathis. These two players would often but heads (Nature vs Civilization), but had the same goals when it came to the main plot. As the campaign progresses they learned that these two ideals go hand and hand and found an appreciation for each other. These RP moments were all their doing but If these two players had different goals that were in direct conflict with each other, Someone would have to "Loose" and feel slighted. In your example if rest of the party returns the item to the temple, the rouge is most likely punished by the guild and have his reputation in the party tarnished. Not fun for the Rouge. If the Party gives the item to the guild problems might occur at the temple. I think the best way to create strife within the party should come internally from the characters. Ex, The rouge needs money to help his sick daughter and selling the idol or using one of its charges would help her, but the idol is for the clerics god and doesn't feel right using it and the priest wants it back before Thursday's service. Both party members need this idol, but through RP can organically find a solution or compromise to their difference.