The post in question contains the following questions:
- Are there any other rules for renouncing an oath are replacing it with another one?
- If presented with such problem as a GM, how would you rule the situation?
- Would he face some curse? Would he lose access to clerical spells for being irreligious or would his conviction to the Cause be enough to retain spellcasting ability? Could that warrant or require change of alignment? [In other words, what are the consequences of doing this]
First off, these are 3 separate questions and so should be asked in different questions. The third really could be subsumed into either the first or second, and a good answer to either one would explain enough to not warrant asking it anyway.
Second off, "Are there any other rules for renouncing an oath are replacing it with another one?" is a stackable question, it clearly has an answer and it can be found. Meanwhile, "If presented with such problem as a GM, how would you rule the situation?" is pretty much the definition of an opinion-based question. It's asking for opinions and is an idea-generation question.
If the question were edited to be focused on that first question then I would vote to reopen it, but as long as it has 2 questions and 1 is opinion based it should stay closed.