Do you believe it because you see the evidence of it and also find no evidence of it’s opposite? Or do you reject non-doership because you don’t wish to accept its implications?
So what does the evidence of your experience tell you about what-is?
And before you come to any conclusions, have you applied your discrimination, observation, and reason wholeheartedly to the question of freewill and doership? Have you brought dispassion and objective scientific scrutiny to bear, along with real fearless integrity and willingness to accept, whatever the cost, the truth of what you see?
Like a true scientist of the Self, have you endeavoured to disprove what you seek to prove? Have you rooted out your own prejudice and preferences? Not cruelly, but tenderly; but also surgically, methodically. Merciless but kind; like you’re identifying and removing a tumour, with precision and purpose, and all the time the whole procedure is born from and occurs within the context of compassion.
This knowledge is Self knowledge, this inquiry is Self inquiry, and therefore only your own self honesty can deliver the truth. Delusion can only be dispelled when you decide within yourself that it’s untenable and unwanted.