God makes mistakes
Christian theology claims the God is perfect. However, there is plenty of evidence in the Bible and in reality that contradicts this claim.
Many other mythologies consider their Gods to be capable of mistakes and of being deceived.
Based on observations of the world
God does not intervene in human evil and he presumably created natural evil. This raises the classic problem of evil.
If he designed the universe, there are many flaws in the design. This is the argument from poor design.
"The LORD regretted that he had made human beings on the earth, and his heart was deeply troubled. "
"I regret that I have made Saul king, because he has turned away from me and has not carried out my instructions."
"And the LORD repented of the evil which he thought to do unto his people."
- "The Hebrew Bible is full of examples of divine fallibility. This God admits mistakes, such as flooding the world; God argues with humans, such as Abraham; God changes course, as in the case of Sodom and Gomorrah: God gets frustrated and angry; as in the case of the golden calf; and God relates to people, sometimes as with Moses, even face to face. Why would a God who was all-knowing and all-powerful make a mistake, or change course, or argue, or get angry? Why would such a God not create a world as perfect as God is? "
Based on the Biblical account, God has poor planning skills.
Old and New Covenant
God makes an "everlasting covenant" Genesis 17:7 which he then has to revise to fix its shortcomings.
- "Later, we are told that there was something wrong with the first covenant (the agreement that God made with the Israelites at Mt. Sinai). The people couldn't keep their part of the deal. God knew they couldn't, but he made the covenant with them, anyway. "
Apologists claim that God does not change his mind because he is unchanging. However, it is hard to reconcile this with the Bible. They claim that God merely changes his approach to dealing with man given the different situations (dispensationalism).
Other apologists think that God does not have definitive knowledge of the future. This gives an opportunity for humans to derail his plans. 
Allah supposedly was the ultimate author of the Qur'an. However, Islamic scholars claim it is written as a progressive revelation which revises/corrects earlier revelation. This is known as abrogation or Naskh in Arabic. A perfect God could have authored it correctly in one attempt.
"Whatever of Our revelations We repeal or cause to be forgotten, We will replace them with something superior or comparable."
- "Allah claims to know what is best but he openly admits that he doesn’t know best. If he did he would not need to abrogate his revelations. "
The Qur'an is full of contradictions  and since Allah is supposedly the author, he is capable of error. Abrogation conveniently provides a way for humans to interpret away any contradictions or shortcomings of Allah in the Qur'an.
- ↑ Alexander, Hanan A., Teaching theology in conservative ideology: historical Judaism and the concept of education, Conservative Judaism, vol. XLVIII, no. 4 (summer 1996), PP. 35-53
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