Is the statement that it is impossible to see God in this world and the hereafter a corrupt belief that necessitates entering Hellfire due to its contradiction of definitive texts from the Qur’an and Sunnah?

Believers will see their Lord in Paradise. This is supported by the Qur'an, the Sunnah, and the consensus of the Companions and their Successors. "Al-Husna" (the best reward) is Paradise, and its increase is the vision of Allah's Noble Face.

As for seeing Allah in this world, it is rationally possible but not Islamically actualized, because no one will see their Lord until they die. As for what was narrated from Ibn Abbas that the Prophet saw his Lord on the night of the Mi'raj, the correct view is that the Prophet saw a light, which was the veil.

The creed of the Ahl al-Sunnah (Sunnis) is that seeing Allah is rationally possible, and it will occur in the Hereafter for believers, not for disbelievers. As for seeing Him in this world, it is rationally permissible but does not occur Islamically.