Hi Sarath ,
To the best of my understanding and experience , doubt is nothing but a very natural mental ingredient, that arises within us from time to time depending on the sensations that is coursing within the body and over the body at any given point of time . The severity of doubting also greatly depends upon the intensity of sensations that we feel . Internally one may doubt about oneself , the ability , not having enough merits, probably having offended an elder or noble person in some life time or the other , which are just excuses ,giving strength to Mara ( personification of our weaknesses ) . Externally , we may tend to doubt , the teacher , the teaching . All this boils down to nothing but the sensations that courses within us any given moment in time . i am sorry , i am repeating this, and you may well know better than me , but sensations and their nature of change are most vital and pivotal in the discovery of all the Buddhas ( neuro-chemical secretions , also known as asvaas ) .
If we read the Mahasatipathan Sutta , it becomes all the more clearer how important this is . One may also feel at times , that doubt may be present within the mind , but it does not trouble , going on to show that the mind experiences doubt without attachment. At times doubt may be present , troubling us badly , showing that the mind experiences doubt with attachment . This holds true for all the mental hindrances also . Similarly for pleasant sensations . In any given day the mind courses like a river , attached and detached to the many pleasant , unpleasant and neutral sensations , with or without detachment , giving rise to a new " me " every moment .This phenomenon one clearly sees for oneself and in all other people , irrespective of nationality , status , caste or creed . Unshakeable faith and reverence to the Buddhas , the Dhamma and the Sangha , thus gets born and established , and one walks on regardless with all the thrill