What is the rationale behind the concept of special pleading when it comes to arguments for the existence of God?

Special pleading is a logical fallacy where someone applies different standards or rules to a particular situation, often to support their own argument. In the context of arguments for the existence of God, special pleading can occur when believers use different criteria or exceptions to justify their belief in God, while not applying the same standards to other beliefs or claims. This can weaken the overall credibility of the argument for God's existence.