Vitalism is the philosophical doctrine that life has a quality independent of physical and chemical laws, such as an immaterial soul. It therefore is opposed to naturalism, the belief that only the natural world exists.
Vitalism is also the basis for a the modern spiritual belief in a "life force" or energy. This "force" has been roundly rejected by science, but vitalist thinking has persisted in religious thought ever since, and is widely accepted by many religious traditions, including fundamentalist Christianity and the New Age movement. It is also an important influence on alternative medicine and other brands of pseudoscience.
Vitalism is an ancient and likely universal premodern belief. "Soul" and "spirit" can easily be interpreted as vital force. The ancient Greek atomists, well-known for their philosophical materialism, believed that there are vital-force (soul) atoms as well as other kinds of atoms. Aristotle even went so far as to identify three kinds of vital force: the vegetable soul, the animal soul, and the rational soul.
Though it is widely believed to have become discredited by the 1828 synthesis by Friedrich Wöhler of urea from ammonium cyanate, that appears to be a myth. Anthony Cheng has written on The Real Death of Vitalism : Implications of the Wöhler Myth (Penn Bioethics Journal, vol. 1, iss. 1):
The Wöhler Myth, as historian of science Peter J. Ramberg calls it, originates from one account by Bernard Jaffe, the author of a popular history of chemistry in 1931 that is still in print today. “Ignoring all pretense of historical accuracy, Jaffe turned Wöhler into a crusader who made attempt after attempt to synthesize a natural product that would refute vitalism and lift the veil of ignorance, until ‘one afternoon the miracle happened’”
(Ramberg, Peter J. (2000) The Death of Vitalism and the Birth of Organic Chemistry. Ambix, 47(3),170-195.)
But it was nevertheless counterevidence against a common view at the time, notably advocated by Jöns Jacob Berzelius, that many compounds, the "organic" ones, could only be made by living things. The others are "inorganic". Wöhler's synthesis would likely have remained a curiosity if it had not been followed by many others. But it was. In 1845, one of Wöhler's students, Adolph Kolbe, succeeded in making acetic acid from inorganic compounds, and in the 1850's, Marcellin Berthelot succeeded in synthesizing numerous organic compounds from inorganic precursors, including methyl alcohol, ethyl alcohol, methane, benzene, and acetylene. They and their colleagues also tackled larger molecules, showing that they were composed of smaller ones.
This work thoroughly discredited that particular vitalist theory, though there were many other areas that vitalists could point to. Some of them indeed did, like one of the last reputable vitalists in biology, Hans Driesch. In 1895, he made an odd discovery: he could take a fertilized sea-urchin egg that had started dividing, split it in two, and watch the two halves develop into two complete sea urchins, instead of two halves of one sea urchin. He concluded from this that there was some "vital force" responsible for development. But it was later discovered that in their first few divisions, a sea-urchin embryo's cells are uncommitted to any particular fate. That commitment only happens later, and Driesch had proposed a sort of "vital force of the gaps", something like a God of the gaps. Stem cells are well-known uncommitted or partially-committed cells.
Vitalists could claim that organism metabolism involves vital force, but around then, biologists started discovering counterevidence. Eduard Buchner, discovered in 1897 that yeast-cell contents could cause fermentation in the absence of whole yeast cells. He followed up in 1903 by making the first discovery of one of the enzymes responsible (zymase). His successors then mapped out many metabolic pathways in great detail, including biosynthesis ones.
But not long after Buchner's work, Jacques Loeb published in 1912 a landmark work, The Mechanistic Conception of Life. He described experiments on how, as Bertrand Russell put it (Religion and Science), a sea urchin could have a pin for its father. He also offered this challenge:
... we must either succeed in producing living matter artificially, or we must find the reasons why this is impossible.
(pp. 5-6). It looks as if he was challenging vitalists to show that vitalism is more than some theory of vital force of the gaps. In pp. 14-15, he took another swipe at vitalism:
It is, therefore, unwarranted to continue the statement that in addition to the acceleration of oxidations the beginning of individual life is determined by the entrance of a metaphysical "life principle" into the egg; and that death is determined, aside from the cessation of oxidations, by the departure of this "principle" from the body. In the case of the evaporation of water we are satisfied with the explanation given by the kinetic theory of gases and do not demand that to repeat a well-known jest of Huxley the disappearance of the "aquosity" be also taken into consideration.
Over the twentieth century and continuing to the present day, molecular biologists have discovered numerous molecular-scale mechanisms, like the well-known carrier of heredity DNA and its relative RNA. Even though some problems, like development, continue to be very difficult, biologists have yet to find any trace of vital force.
Mind-body dualism or separable-soulism is essentially a vitalist theory of mind and consciousness. Scientific work on mind has not progressed as far as with biological processes in general, but it has the same trend: not a trace of separable soul to be found.
 New Age/alternative medicine
In New Age, spiritual virtue or power is said to be achieved by manipulation or enhancement of a mysterious force sometimes called qi, Orgone, the bioenergetic field, or "energy". Modern New Agers might use Quantum woo instead of the older traditions of Faith healing to attract customers who believe that a Harmonized Quantum-Synthetical Channelling Energetic Alignment System is a good way to prevent cancer. Quacks combine vitalism and New Age with Alternative medicine, promising to cure a wide range of different afflictions using pseudoscientific methods such as Acupuncture and inappropriate Chiropractic. Those few instances when customers do experience results are likely due to the Placebo effect or the disease getting better on its own. Those who question claims made by vitalists are typically buried in a pile of excessively confusing woo jargon.
Therapeutic touch practitioners are those who claim that they can directly experience the energy promoted by vitalism and control or channel that energy in such a way that a person would magically become better. Note that the "energy" commonly referenced by such quacks is not the same as the scientific ability to do work. Therapeutic touch may also hide behind even less understood terms like rays and vibration or between made-up things called Auras. There has yet to be any scientific study that has not proven these variations of vitalism utterly wrong.
 In organized religion
Vitalism is not particularly common in modern organized religions, but the philosophical concept of an immaterial spiritual soul goes well with some types of fundamentalist Christianity, such as born-again Christians.