In An Essay on the Development of Christian Doctrine (Chapter 1, Section 2:8), Newman shows that religion is necessary for...
+ Conscience (and the doctrine of a Moral Governor)
+ The Social Principle
+ Praying for the Dead
+ Rites and Ceremonies
+ Cultivation of Awe and Love towards what is great, high, and unseen.
Newman quotes Guizot at length on this matter.
"If we reduce religion," he says, "to a purely religious sentiment … it appears evident that it must and ought to remain a purely personal concern. But I am either strangely mistaken, or this religious sentiment is not the complete expression of the religious nature of man. Religion is, I believe, very different from this, and much more extended. There are problems in human nature, in human destinies, which cannot be solved in this life, which depend on an {50} order of things unconnected with the visible world, but which unceasingly agitate the human mind with a desire to comprehend them. The solution of these problems is the origin of all religion; her primary object is to discover the creeds and doctrines which contain, or are supposed to contain it.
"Another cause also impels mankind to embrace religion … From whence do morals originate? whither do they lead? is this self-existing obligation to do good, an isolated fact, without an author, without an end? does it not conceal, or rather does it not reveal to man, an origin, a destiny, beyond this world? The science of morals, by these spontaneous and inevitable questions, conducts man to the threshold of religion, and displays to him a sphere from whence he has not derived it. Thus the certain and never-failing sources of religion are, on the one hand, the problems of our nature; on the other, the necessity of seeking for morals a sanction, an origin, and an aim. It therefore assumes many other forms beside that of a pure sentiment; it appears a union of doctrines, of precepts, of promises. This is what truly constitutes religion; this is its fundamental character; it is not merely a form of sensibility, an impulse of the imagination, a variety of poetry.
"When thus brought back to its true elements, to its essential nature, religion appears no longer a purely personal concern, but a powerful and fruitful principle of association. Is it considered in the light of a system of belief, a system of dogmas? Truth is not the heritage of any individual, it is absolute and universal; mankind ought to seek and profess it in common. Is it considered with reference to the precepts that are associated with its doctrines? A law which is obligatory on a single individual, is so on all; it ought to be promulgated, and it is our duty to endeavour to bring all mankind under its {51} dominion. It is the same with respect to the promises that religion makes, in the name of its creeds and precepts; they ought to be diffused; all men should be incited to partake of their benefits. A religious society, therefore, naturally results from the essential elements of religion, and is such a necessary consequence of it that the term which expresses the most energetic social sentiment, the most intense desire to propagate ideas and extend society, is the word proselytism, a term which is especially applied to religious belief, and in fact consecrated to it.
"When a religious society has ever been formed, when a certain number of men are united by a common religious creed, are governed by the same religious precepts, and enjoy the same religious hopes, some form of government is necessary. No society can endure a week, nay more, no society can endure a single hour, without a government. The moment, indeed, a society is formed, by the very fact of its formation, it calls forth a government,—a government which shall proclaim the common truth which is the bond of the society, and promulgate and maintain the precepts that this truth ought to produce. The necessity of a superior power, of a form of government, is involved in the fact of the existence of a religious, as it is in that of any other society.
"And not only is a government necessary, but it naturally forms itself. ... When events are suffered to follow their natural laws, when force does not interfere, power falls into the hands of the most able, the most worthy, those who are most capable of carrying out the principles on which the society was founded. Is a warlike expedition in agitation? The bravest take the command. Is the object of the association learned research, or a scientific undertaking? The best informed will be the leader ... The inequality of faculties and influence, which is the foundation of power in civil life, has the same effect in a {52} religious society ... Religion has no sooner arisen in the human mind than a religious society appears; and immediately a religious society is formed, it produces its government."
Guizot, Europ. Civil., Lect. v., Beckwith's Translation