What is the way to deal with the whispers of disbelief (kufr), polytheism (shirk), atheism (ilhad), and not believing in the existence of the Creator, or that God is the Creator? Do these whispers indicate the closing of the doors of mercy? And how can one repent from them and regain God's pleasure?

Hating whispers (waswasa) and feeling aversion towards them is a sign of sound belief, and doubt is a devilish whisper. The polytheists believed that Allah is the Creator, so how about a Muslim? Many Quranic verses indicated their affirmation that Allah is the Creator of everything. To get rid of whispers, completely turn away from them, preoccupy yourself from them, and seek out the gatherings of scholars who adhere to the Sunnah, and stay close to them to benefit and attain steadfastness.