Master Huijing, responding to a monastic’s questions about difficulties in Pure Land practice; November 1998:
English translation by Jingtu 

Thank you for your letter. You have practiced diligently, yet missed the essence.

As Master Shandao says, there are “primary practice” and “miscellaneous practice” in Pure Land Buddhism. By undertaking primary practice, we are 100% certain of being reborn in the Pure Land’s Realm of Rewards. Among miscellaneous practitioners, however, only one or two out of a hundred, three or five out of a thousand, will do so. Rebirth in the Realm of Rewards will be hard.

You are doing miscellaneous practice. Though you can dedicate its merit  towards rebirth, it is remote from Amitabha Buddha and not intimate, far from him, not close. That’s why Amitabha’s light does not embrace you constantly.

Master Shandao says:

Amitabha’s body is like a golden mountain;
The light of his special features shines in all directions.
Only those who recite his name are embraced by his light;
Know that his Fundamental Vow is the most powerful.

He also teaches:

Amitabha’s special features number 84,000;
Their light illuminates the ten directions.
It shines not on those with other karma,
Seeking only name-reciters who aspire to rebirth.

And further notes:

The light of Amitabha is luminous,
Embracing only those who recite his name.

However many practice sessions you have each day, each should involve recitation of the Great Six-Character Name “Namo Amitabha Buddha.” Amitabha accomplished his name from perfect virtue and uses it to embrace all things. With each recitation, all merit and virtue are complete. What does it lack, so that you need to look elsewhere -- especially since rebirth in the Pure Land depends not on our own effort but entirely on Amitabha’s power?

Therefore it matters not whether a sentient being is of high or low status, male or female, young or old, light or dark, wise or foolish. Nor does it matter if the being has heavy or light karmic offenses, self-cultivation or no self-cultivation, a pure or impure heart, focused or distracted thoughts. None of this matters. So long as we recite Amitabha Buddha’s name, we will certainly be reborn in the Pure Land. Moreover, through the unfathomable power of Amitabha’s Fundamental Vow, even those who have committed the Five Gravest Transgressions and the Ten Evil Actions, as well as Dharma-slandering icchantika (vilest, most deluded beings), can be reborn.

To rely on the power of the Fundamental Vow means to firmly believe in and accept the deliverance of Amitabha Buddha, and to recite his name single-mindedly and exclusively. So in terms of rebirth, self-power does not matter, only other-power.

Those who seek rebirth in the Pure Land should first understand Amitabha’s Fundamental Vow. On our behalf, Amitabha has already accomplished the Land of Bliss and the virtues and merit needed for rebirth there. He has also redeemed all the karmic debts we accumulated since time immemorial. And Amitabha long ago completed the various virtues and merit we would need to be reborn in the Land of Bliss. Because we neither know nor believe, we have not been able to accept and receive Amitabha’s merit, and continue to suffer reincarnation.

Today, if we know, believe, recite the name and want rebirth in the Pure Land, we will assuredly achieve it by the power of Amitabha’s Vow. Such faith would be eternal, undeviating, consistent from start to finish. From morning to night, from dusk to dawn, we single-mindedly recite the name of Amitabha. We do not recite the names of other Buddhas or Bodhisattvas, or various sutras or mantras. This is what Master Shandao earnestly urged us to do.

He says:

[Shakyamuni] Buddha’s underlying wish is that sentient beings
recite Amitabha’s name single-mindedly.

And:

To recite Amitabha’s name single-mindedly and without variation, whether walking, standing, sitting or lying down, whether for long or short periods – that is the karma of assurance. It is so because it accords with Amitabha Buddha’s vow.

Does it make sense for practitioners determined this lifetime to achieve rebirth not to act accordingly?

During every practice session, it is enough that you recite the Great Six-Character Name. Let go, leave behind all other scriptures and mantras. Do not cling to them stubbornly. The rest of the time, read the publications of the Pure Land school and put aside all other texts. You will know why, if you re-read Master Honen’s Collection on Choosing Buddha-Recitation According to the Fundamental Vow (Senchakushū).

Master Shandao says:

The Land of Bliss is a realm of unconditioned nirvana;
It’s hard to be reborn there by practicing assorted virtues according to circumstances.
The Tathagata selects the key method –

He teaches us to recite Amitabha’s name with two-fold exclusivity.