Rejoing covenant question

Hi guys if i rejoin covenant do i need to do all the campaign quest agian? Im at renown 25 now

Yes you’ll have to redo the campaign and re raise your renown. It can be quite burdensome, so make sure it’s something you wanna do. Blizzard also has some info here on it

https://us.battle.net/support/en/article/279887#:~:text=All%20Covenant%20specific%20benefits%20of,PvP%2C%20Covenant%20Callings%20and%20dungeons.