"Why is that one person is ready for the nembutsu and others obviously not. And assumed the nembutsu comes only from the Buddha to us, as taught by Shinran, does the Buddha chose between those he wants to save now and those he does´nt want to save yet?"
Imagine that somebody loves you unconditionally, but you do not care. The love of that person is always upon you, but because your eyes are closed, you cannot feel his or her love.
Some might ask: what do we have to do in order to receive shinjin?
Master Rennyo said in Rennyo Shonin Goichidai Kikigaki (Thus I Have Heard from Rennyo Shonin):
"Regardless of our doubts, if we listen intently with our entire being, we will be given shinjin because of Great Compassion. The Buddhist teaching begins and ends in hearing."
So, in our tradition, listening to the teaching is the most important practice. You have to listen again and again, and one day, you will become open and you will receive shinjin. The words "we will be given shinjin because of Great Compassion" shows that shinjin comes from Amida, but the first part "if we listen intently with our entire being" shows what we have to do, if we wish to receive the gift of faith from Amida. As my nembutsu friend, Jason Ranek said in his poem:
"Uncover your cup
To receive the Dharma rain,
Then faith, and the Nembutsu,
Will naturally arise."
If somebody does not listen deeply to the teaching, but is filled with ideas of self power, he cannot receive shinjin and nembutsu (which is the natural manifestation of shinjin). Shinjin and nembutsu are not forcibly imposed in our hearts by Amida Buddha, so if somebody does not show interest in the Buddhist teaching and especially in the teaching about the Primal Vow of Amida, he cannot receive shinjin.
Things are very simple and yet very profound. My opinion is that we should not complicate our minds, but listen to the Dharma again and again, and faith will be given.
"Amida has no mercy since Amida only saves those who says His Name". Master Rennyo answered him with the poem: "There is no heart far from Amida, but a covered bowl of water cannot reflect the moon.”