I'm of the opinion that almost all religious and spiritual thought is reasoning at it's core, sometimes philosophical and sometimes practical.
For example, I do not think of the Bhagavad Gita as a book of knowledge with hard facts in it. Rather I see it as a book on spiritual philosophy derived from reason, and it's put into the format of a dialogue between the knowing philosopher (Krishna) and the one who wants to know and is moving the conversation forward with questions. Plenty of ancient Greek and more recent western philosophy is set up this way.
So for me this means:
1. Religion (as a whole) should not be written off as nonsense that is completely separate from critical reasoning.
2. There is nothing wrong with picking certain ideas from religion/s and ignoring others.
I'm particularly interested to hear what some atheists think about this. The ones I've said this to in person haven't liked it too much. Lawrence Krauss thinks we should throw out all religious thought because some of it (well, maybe a lot of it depending on which religion) is wrong.
Am I right? Is religion reasoning?
Yes, religion is a form of reasoning. The opposition between Science and Religion is historically very recent, beginning in the 19th century, particularly when Evolution brought into question the Biblical account of creation. Before then Science, Religion and Philosophy were all in
roughly the same discipline called "Natural Philosophy". Concepts of Natural Law and Natural Rights, were pivotal to the development of liberalism and our conception of 'human rights' and had religious roots in Judaeo-Christian ethics. Secular Societies therefore implicitly have a bias towards religious patterns of reasoning.
The conflict between religious belief and scientific evidence has grown over time. Philosophically, Religion and Science continue to overlap and so many discoveries have religious interpretations (Is the concept of Big Bang as the origin of the Universe actually another version of Creation for example?), but as Science has become professionalized it has become more divorced from explicit discussion of philosophical problems over the nature of reality (and religions place in it).
Personally, I do not hold the view that religion should be written off despite being an atheist. If you accept the proposition that God does not exist, but is a projection of man, religion still has something to tell you something about human beings, our history and culture. Even in an Atheist society, religion still holds some value by telling us part of the story of our humanity and our struggle to define ourselves as a species. Religious questions still need secular, scientific or atheist answers.
However, on you're second question, I'm more skeptical, as I take the side of science. Whilst Religion and science do overlap, the conflict between them is undeniable and I take the side of evidence over faith. I would only therefore accept an idea if I felt it had validity is a secular sense and has some case for being objectively true. The fact it is religious is co-incidental. Religion is not a substitute for Science, but can complement it.
That said, the philosophical assumptions of religion continue to predominate such as moral ideas about free will and individual rights and responsibility. The concept of the soul continues to live on in a secular guise as our understanding of "human nature" as the source of our understanding of ethics and society. Science has yet to become consciously aware of it's religious roots and capable of being 'atheist' in it's own right, particularly to replace religions role as a way of understanding morality, the problem of responding to death and our place in the universe. This would require a much more open and philosophical approach to science and even this does not automatically entail it would be anti-religious. we can still learn things from religion and we should.
The question is ultimately is whether religion will become an out-dated form of reasoning, and on that I remain uncertain as there is no obvious substitute to it. Religion isn't out right "false" or "wrong", but it is arguably incomplete or distorted because it lacks the ability to prove it's claims in a rational or scientific way.
