觀無量壽佛經疏 4.50

4.50

二、從亦信因果下至無上道心已來，正明第六門中受法不同。即有其三。一明所信因果不定，或信不信，故名為亦，或可亦同前深信也。又雖信不深，善心數退、惡法數起，此乃由不深信苦樂因果也。若深信生死苦者，罪業畢竟不重犯。若深信淨土無為樂者，善心一發永無退失也。二明信雖間斷，於一切大乘不得疑謗，若起疑謗者，縱使千佛遶身，無由可救也。三明已上諸善似亦無功，唯發一念厭苦，樂生諸佛境界，速滿菩薩大悲願行，還入生死普度眾生，故名發菩提心也。此義第三福中已明竟。

Second, from 'also believes in cause and effect' down to 'supreme aspiration for awakening,' directly clarifies the differences in receiving the Dharma in the sixth gate. There are three points: First, clarifies that belief in cause and effect is indefinite—sometimes believing and sometimes not believing, hence called 'also'; or it can mean 'also' having deep faith like the previous [grade]. Furthermore, although there is faith, it is not deep; good thoughts frequently regress and evil phenomena frequently arise, which is due to not deeply believing in the cause and effect of suffering and bliss. If one deeply believes in the suffering of saṃsāra, one will ultimately never repeat sinful karma. If one deeply believes in the unconditioned bliss of the Pure Land, once a good thought arises, one will never regress. Second, clarifies that although faith may be intermittent, one must not doubt or slander any part of the Mahāyāna; if one gives rise to doubt or slander, even if a thousand Buddhas were to surround one's body, there would be no means of rescue. Third, clarifies that while the aforementioned goods seem to have no efficacy, if one generates merely a single thought of repenting suffering, delights in birth in the realm of the Buddhas, swiftly fulfills the bodhisattva's vows and practices of great compassion, and returns to saṃsāra to universally deliver sentient beings, it is called generating bodhicitta. This meaning has already been explained in the third blessing.