Can a puthujjana have unshakable faith in the Buddha-Dhamma?

I read the following on the internet: > According to my present understanding of Dhamma, nobody will be able > to shake my faith. Can a puthujjana (unenlightened commoner still immersed in self instinct) have unshakable faith in the Buddha-Dhamma? What happens if a puthujjana does a meditation retreat and freaks out when in solitude or experiencing ego-death? What are the conditions or criteria for unshakable faith (acalā saddha)?