When doubt arises in relation to a spiritual practice, it is normally a big problem because the only tools available to deal with the problem are the ones the person has doubt in. The good news is that insight meditation is unique in the sense that we are not asked to accept truths unconditionally. On the contrary, we are encouraged to observe and see things for ourselves.
If we experience doubt in the value of the insight meditation practice, that is not a barrier to continuing with it. This is because, the prescription for such a problem is to observe the doubt the way it is without trying to make it go away.
If we take for example, the building in the above photograph, there is no question that it is a large building and wishing that the building will disappear will not make it go away. That building will probably be there for a long time. However, if we observe the building carefully, it becomes apparent that there is nothing really objectionable about it. Perhaps we don’t like this particular style of architecture but even if we had to walk past it every day, that would not be so bad.
Similarly, when it comes to conditions of the mind such as doubt, what the Buddha pointed out to us is that it’s not the condition that is the problem. It is our view of it that hinders us. When viewed correctly, doubt is just another element of nature. We are the ones that have decided that we don’t like it and don’t want it to be there. However, that decision is arbitrary because doubt can have positive aspects to it by pointing out the way to deeper understanding.