What is the ruling on doubting the purity of everything touched by non-Muslims, and how should a Muslim act in this situation?

Do not dwell on whispers [waswas], for they lead to great evil; rather, turn away from them and pay them no mind. The ruling of impurity (najasah (definition)) does not transfer merely by doubt, because the original state is purity (taharah (definition)). A disbeliever is not ritually impure in a tangible sense; rather, their impurity is spiritual. Their hand and hair are pure, and one should not deviate from this principle except with certainty. A human being does not become impure by death, whether they were Muslim or disbeliever.