Are the thoughts associated with doubt in miracles, which the soul detests and recoils from, considered disbelief or merely a whisper (waswas)?

What you experience of whisperings (waswas) does not constitute apostasy, as long as you detest them. The cure for yourself is to completely turn away from indulging with Satan in thought, and to seek help through the remembrance of Allah and supplication to Him. You are not held accountable for the whisperings of Satan that afflict you as long as you have not spoken them. For the Messenger of Allah, peace and blessings be upon him, said: "Indeed, Allah has forgiven for my Ummah whatever whisperings or thoughts occur within themselves, as long as they do not act upon it or speak of it." We advise you to seek religious knowledge, read books that strengthen one's creed, and consistently remember Allah.