To me a strength of 5E is that no class is essential. And though the cleric can (mostly) be replaced with other classes, so can every other class. They are all replaceable.This is a good point, and I should clarify my position a little better. My group doesn't just see the cleric as "eh not the class I want to play", they see it as "this is a flaw in 5e....its a bad class that is a bad design".
So in some ways showing them the cleric is good is in the same breath saying "this is not a flaw in the game".
Maybe because the OP asked us to?If no one in your group wants to play a cleric, there's no reason to convince them otherwise. It is unnecessary for every class to get played at some point in every group.
... help me make the cleric look interesting and cool to play.
As a rule, trying to convince people to want to play something they don't want to play is... a poor use of time.I am sure there are many people on the board who would disagree with my group's notions, so tell me where they went wrong, help me make the cleric look interesting and cool to play.
2) Cleric spellcasting isn't all that interesting. Sure spiritual weapon is decent, guidance is the best cantrip, spirit guardians is amazing (and therefore boring, as every cleric on the planet has it), and bless is the best buff in the game. And that's it.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.