Jodo Shu teaches that we can hardly attain nirvana in this secular world, but that after Birth in the Pure Land everyone can enter nirvana. Firstly, we will be welcomed to the Pure Land by Other Power through our practice of Nembutsu. After the Birth we will be able to attain nirvana.
Shinran Shonin says,
"When the one thought-moment of joy arises, Nirvana is attained without letting go of our worldly desires."
I think this sentence means that the experience of blissful feeling we can enjoy when we received the true belief is the same experience that we can have when attaining nirvana, which is the final goal of Buddhism. Although these are extremely precious words, if we aim for this state of mind, it may become very difficult to approach.
Jodo Shu doesn't go that far. Of course belief is important, but Jodo Shu doesn't connect belief with nirvana. (I also think it's a slight difference of terminology.)
What's important is to continue the practice of Nembutsu with all our heart.
Although Amida Buddha is the buddha of immeasurable life and immeasurable light, He is not an absolute being like God.
i) According to the scripture, a king became a convert to Buddhism, made the 48 Vows, practiced asceticism, attained Buddhahood and became Amida Buddha. Amida is not the creator of the universe.
ii) Amida Buddha is not only one savior. For us followers He is the only savior, but there are many other buddhas in Mahayana. Amida Buddha is one of those buddhas preached in Mahayana Buddhism.
iii) There is no unbridgeable gap between the being of Amida and us. Someday led by Amida, we will be able to attain Buddhahood as He attained it.
Although the pieties in Christianity and Pure Land Buddhism have something in common, the backgrounds of them are quite different. It is also the difference between Buddhism and Christianity. We follow a school belonging to Buddhism.