Buddha's Parable of The Poisoned Arrow

Buddha refused to be drawn into questions regarding how the universe began. He had concluded that dukkha (suffering, 苦) were caused by desire (the four noble truths 四諦) and proposed his own solution (the eight-fold path 八正道) to nirvana. He felt that how the universe began is irrelevant to the solution. He gave the parable of the arrow as an analogy:

QUOTE
The Parable of the Arrow (Majjhima-nikaya, Sutta 63)
The Buddha was sitting in the park when his disciple Malunkyaputta approached him. Malunkyaputta had recently retired from the world and he was concerned that so many things remained unexplained by the Buddha. Was the world eternal or not eternal? Was the soul different from the body? Did the enlightened exist after death or not? He thought, "If the Buddha does not explain these things to me, I will give up this training and return to worldly life".
Thus, he approached the Buddha with this question, who replied:
"Suppose, Maunkyaputa, a man were wounded by an arrow thickly smeared with poison, and his friends and companions brought a surgeon to treat him.  The man would say: 'I will not let the surgeon pull out the arrow until I know the name and clan of the man who wounded me; whether the bow that wounded me was long bow or crossbow; whether the arrow that wounded me was hoof-tipped or curved or barbed.' All this would still not be known to that man and meanwhile he would die.  So too, Malunkyaputta, if anyone should say: 'I will not lead the noble life under the Buddha until the Buddha declares to me whether the world is eternal or not eternal, finite or infinite; whether the soul is the same as or different from the body; whether an awakened one ceases to exist after death or not,' that would still remain undeclared by the Buddha and meanwhile that person would die.
Whether the view is held that the world is eternal or not, Malunkyaputta, there is still birth, old age, death, grief, suffering, sorrow and despair – and these can be destroyed in this life! I have not explained these other things because they are not useful, they are not conducive to tranquility and Nirvana. What I have explained is suffering, the cause of suffering, the destruction of suffering and the path that leads to the destruction of suffering. This is useful, leading to non-attachment, the absence of passion, perfect knowledge."
Thus spoke the Buddha, and with joy Malunkyaputta applauded his words.
UNQUOTE

The parable in Chinese:
就好比有人身中毒箭，很痛苦，他的親人憐憫他，想為他解除中毒箭之苦，為他請來專門治療箭傷的醫生。然而他卻想：箭不可拔，應先知道射箭的人，姓什麼？名什麼？是長得高、矮、胖、瘦？膚色如何？又是哪一族人？住在哪個方向？所用的弓、弓扎、弓弦、箭桿、箭纏、箭羽、箭頭的材質、顏色？製造箭頭的人，姓什麼？名什麼？他的長相與身份又是如何？結果，「彼人竟不得知，於其中間，而命終也。」
中阿含經《箭喻經》

It is true that the patient does not need to know too much about the poisoned arrow in order to receive the treatment, especially if the information is irrelevant. However, Buddha was the doctor, not the patient. Buddha was providing a cure for dukkha. If God exists and created the universe, Buddha's cure could be wrong, because he did not take into account this Very Important Person. You cannot live in an universe that has a Creator and ignore Him, just as you cannot live in a country that has a government and ignore the government. The parable of the poisoned arrow fail to prove that the knowledge about the arrow was irrelevant to the doctor.