Imaam al-Aajurree (rahimahullaah) mentions in his book al-Sharee'ah (pp. 252-253) a debate taking place between a Majoosee (fire-worshipper) and a Qadari (denier of al-qadar):

From Amr bin al-Haytham (rahimahullaah) who said: I went out on a ship to al-Ubullah, I and its qaadee, Hubayrah bin al-Udays. He said: Accompanying us on the ship (for the journey) was a Majoosee and a Qadaree. The Qadaree said to the Majoosee, "Become Muslim." The Majoosee said, "Not until Allaah desires it." The Qadaree said, "Allaah desires it, but Shaytan will not leave you alone." The Majoosee said, "Allaah desires (something) and Shaytaan desires (something), and what Shaytaan desired occurred. This is a strong Shaytaan."

Note

The Majoos (Magians) believe in two gods, a god of light (good) and a god of darkness (evil), and they believe all evil comes from the god of darkness. The Majoosee in this argument overcame the Qadaree and established that the Qadaree's belief entails there is another creator besides Allaah, who is as powerful, if not more powerful than Allaah (we seek refuge in Allaah from such speech). This is because the reality of the saying of the Qadaree is that though Allaah wishes for mankind to be Muslim, He does not actually create their actions through His will (mashee'ah) and creative power, they create their own actions, and Shaytaan influences them in their actions. As a result, there occurs in the creation that which is outside of Allaah's will (mashee'ah) and creative power and Shaytaan's wish (iraadah) dominates Allaah's wish (refuge is from Allaah), because what Allaah desired did not occur but what Shaytaan desired did occur.

Read this article for a correct understanding of al-Qadr with Ahl al-Sunnah wal-Jamaa'ah.