Circular reasoning, also known as circular logic or "begging the question," is a logical fallacy where the conclusion of an argument is assumed in its premises. Circular reasoning is a closed loop of logic that doesn't actually prove anything new. Instead, it restates the initial assumption as a conclusion.
While this type of reasoning seems convincing to those who already accept that A is true, it doesn't provide a reasonable answer for those questioning whether or not A is true.
Argument: "The Bible is 'true' because it's the word of God. We know it's the word of God because the Bible says so."
Fallacy: This argument assumes the Bible's divine authority in order to prove its divine authority.
Argument: "God cannot be wrong because the Bible says so. The Bible cannot be wrong because it is inspired by God."
Fallacy: This argument assumes that God cannot be wrong to prove that God cannot be wrong.
Argument: "Miracles prove that God exists. Only God could perform these kinds of miracles."
Fallacy: This argument assumes God's existence to define miracles, then uses those miracles to prove God's existence.
Argument: "I know God exists because I can feel His presence. Only God could give this kind of peace."
Fallacy: This argument assumes that the feeling of God's presence is proof of God's existence, while assuming God's existence is the only to explain the feeling.
Argument: "God answers prayers, which proves He exists. Only God could have answered this prayer."
Fallacy: This reasoning assumes God's existence to explain answered prayers, then uses those answered prayers as proof of His existence. It doesn't account for unanswered prayers either.
Argument: "God is defined as the greatest conceivable being. The greatest conceivable being must exist in reality (because existing in reality is greater than existing only in the mind). Therefore, God exists."
Fallacy: This argument defines God as necessarily existing, then concludes that He exists.
Argument: "Logical absolutes exist. Only God can account for the existence of logical absolutes. Therefore, God exists."
Fallacy: This argument assumes that only God can account for logical absolutes, which is the very thing it's trying to prove.