Does God not accept the repentance of polytheists, despite His description of Himself as Oft-Forgiving, Most Merciful, and does this contradict His saying, exalted be He: "Say to those who have disbelieved, if they cease, what has passed will be forgiven them"?

The noble verse does not mean that the repentance of polytheists is not accepted. Rather, it indicates that Allah Almighty does not forgive those who die upon disbelief. Whoever embraces Islam is forgiven all past sins, as the Prophet, peace and blessings be upon him, said: "Islam wipes out whatever sins came before it." So, whoever repents from polytheism before their death, Allah forgives them, and the verse is consistent with His Almighty saying: "Say to those who have disbelieved, if they cease, what has passed will be forgiven them."