Waswas concerning Iman is a sign of pure faith, not of weakness — for shaytan only attacks a heart that holds something precious to defend. The Companions came to the Prophet (ﷺ) saying: "We find in our hearts what one of us would consider too grave to even speak of." He said: "Have you indeed found that?" They said yes. He said: "That is clear faith." (Muslim 132). The treatment is fivefold: (1) recognise the source — it is from shaytan, not from your true belief; (2) refuse to dwell on it and turn away to remembrance of Allah; (3) seek refuge in Allah from the accursed shaytan and spit dryly to your left three times; (4) say "I believe in Allah and His Messenger" as the Prophet (ﷺ) instructed (Muslim 134); (5) busy yourself with what benefits — recitation, dhikr, beneficial knowledge — for an idle heart is the playground of waswas. Do not argue with the thoughts; treat them as you treat a thief who knocks at the door — do not open and engage, simply ignore until he leaves.