Yes, natural selection is good science, and can be observed. However, it is a common falacy to equate natural selection with evolution. Just because there is change within a species over time does not equate one species changing into another type or kind of species. Again, there may be adaptative changes within a specific species, brought on (by nature/ by God), but that in no way can equate to or explain the change of one species into another. This is not to say that NO change within a species ever occurs. However, cats will never become elephants, or anything besides a cat. Its ancestor may be a tiger, or a sabre tooth, or a cheetah, or a jaguar, ect. Fish cannot grow legs and lungs (we can discuss the lungfish in further detail if you wish). Microorganisms cannot create themselves out of amino acids.
The stanley Miller experiment that generated amino acids, by the way, presupposed the wrong kind of early environment when he generated amino acids (the basic building block of life). 99% of scientists (including athiests, christians, and those of other faiths) believe that the composition of early earth is entirely different from the composition they had believed to exist. When you duplicate the stanley miller experiment, given the knew knowledge about the composition of early earth, you generate a toxin, rather than amino acids. Oddly enough, the toxin that is generated closely resembles embalming fluid, which is not exactly a great medium for life to "spontaneously" create itself.
As far as mutations, yes, they do occur. As life continues, our DNA gets more and more scrambled, along with all other types of life. However, by definition, a mutation (in the context of DNA) ALWAYS results in the LOSS of information, not in new information being created. This is DEevolution, not change that continually gets better. The only beneficial type of mutation is when LOSS of information turns out to be a positive. For example, a fish that lives on the bottom of the ocean could have mutated (note, it is STILL a fish), and lost its eyes, to a certain extent. Fish on the bottom of the ocean, for the most part, use their eyes very little, if ever. An eye is a very sensative and vunerable organ, so the loss of eyes in a species that lives on the bottom of the ocean would be a beneficial change. However, this is observed very rarely.
Oh, and to say that it does not take faith to believe in evolution is quite funny, if you look at it. To presuppose that there is no faith (believing in something that is not 100% certain) needed for evolution is only possible if YOU have attained 100% of all the knowledge of the universe. Only then is there no need of any kind of faith, because all other options would be exhausted. You may believe that there is better evidence for evolution, which is fine, but there is no person in the world that has knowledge of everything throughout the universe.
Basically, you need to look at creationism, ID, and evolution, and find which has the most evidence. Don't start with the presuposition that miricles and God are impossible, and don't start with the assumption that we cannot know any truth outside of the bible. Then, whichever you find more plausable, go ahead and believe (have faith, of one sort or another) in it.