All that he said is true. Dana liberates us from suffering and poverty. Morality keeps body, speech and mind calm and tranquil, it ends suffering and leads the way to heaven and finally to Nibbana. Samadhi brings joy to our hearts and transforms us into happy and peaceful people. All these meritorious practices and the teachings on their positive results are true.
Hells really exist for people who have done evil and created bad kamma due to a lack of morality.
Merit and demerit are the truth which the Buddha taught. We have no confidence in ourselves but have faith in him because he had already studied, understood, put it to the test and brought it to perfection. The main teachings which he gave us were Morality, Samadhi, and Pa a. We cannot believe in merit and evil because we do not understand our minds. Once we do, and with experience, we will develop faith and doubt will be dispelled.