This is one of the Buddha’s most important quotes:
There is an Unborn, Unoriginated, Uncreated, Unformed. If there were not this Unborn, this Unoriginated, this Uncreated, this Unformed, escape from the world of the born, the originated, the created, the formed, would not be possible.
But since there is an Unborn, Unoriginated, Uncreated, Unformed, therefore is escape possible from the world of the born, the originated, the created, the formed.
Please compare the above to Shinran quoting the Chinese Pure Land master Shan-tao on the nature of the Pure Land:
The land of bliss is the realm of nirvana, the uncreated;
I fear it is hard to be born there by doing sundry good acts according to our diverse conditions. Hence, the Tathagata selected the essential dharma,
Instructing beings to say Amida’s Name with singleness, again singleness.
The Pure Land is the realm of Nirvana, the “escape from the born, the originated, the created, the formed.” Shinran described the Pure Land as “the birth of non-birth,” just as the Buddha described Nirvana as “the unborn.”
The Buddha selected the name of Amida, Namu-Amida-Butsu, as a skillful device (upaya) for bringing ordinary beings like ourselves into the realm of Nirvana. Whether Amida is a literal historical being is beside the point: