Okay, lets give Mr. Madison a Go..
"Whilst we assert for ourselves a freedom to embrace, to profess and to observe the Religion which we believe to be of divine origin, we cannot deny an equal freedom to those whose minds have not yet yielded to the evidence which has convinced us. If this freedom be abused, it is an offence against God, not against man: To God, therefore, not to man, must an account of it be rendered. As the Bill violates equality by subjecting some to peculiar burdens, so it violates the same principle, by granting to others peculiar exemptions. …..Because the Bill implies either that the Civil Magistrate is a competent Judge of Religious Truth; or that he may employ Religion as an engine of Civil policy. The first is an arrogant pretension falsified by the contradictory opinions of Rulers in all ages, and throughout the world: the second an unhallowed perversion of the means of salvation. Because the establishment proposed by the Bill is not requisite for the support of the Christian Religion. To say that it is, is a contradiction to the Christian Religion itself, for every page of it disavows a dependence on the powers of this world: it is a contradiction to fact; for it is known that this Religion both existed and flourished, not only without the support of human laws, but in spite of every opposition from them, and not only during the period of miraculous aid, but long after it had been left to its own evidence and the ordinary care of Providence. Nay, it is a contradiction in terms; for a Religion not invented by human policy, must have pre-existed and been supported, before it was established by human policy. It is moreover to weaken in those who profess this Religion a pious confidence in its innate excellence and the patronage of its Author; and to foster in those who still reject it. A suspicion that its friends are too conscious of its fallacies to trust It to Its own merits. Because experience witnesseth that ecclesiastical establishments, instead of maintaining the purity and efficacy of Religion, have had a contrary operation. During almost fifteen centuries has the legal establishment of Christianity been on trial. What have been its fruits? More or less in all places. Pride and indolence in the Clergy, ignorance and servility in the laity, in both, superstition, bigotry and persecution. Enquire of the Teachers of Christianity for the ages in which it appeared in its greatest luster; those of every sect, point to the ages prior to its incorporation with Civil policy. Propose a restoration of this primitive State in which its Teachers depended on the voluntary rewards of their flocks, many of them predict its downfall. On which Side ought their testimony to have greatest weight, when for or when against their interest? Because the establishment in question is not necessary for the support of Civil Government. If it be urged as necessary for the support of Civil Government only as it is a means of supporting Religion, and it be not necessary for the latter purpose, it cannot be necessary for the former. If Religion be not within the cognizance of Civil Government how can its legal establishment be necessary to Civil Government? What influence in fact have ecclesiastical establishments had on Civil Society? In some instances they have been seen to erect a spiritual tyranny on the ruins of the Civil authority; in many instances they have been seen upholding the thrones of political tyranny: in no instance have they been seen the guardians of the liberties of the people. Rulers who wished to subvert the public liberty, may have found an established Clergy convenient auxiliaries. A just Government instituted to secure & perpetuate it needs them not. Such a Government will be best perpetuate it needs them not. Such a Government will be best supported by protecting every Citizen in the enjoyment of his Religion with the same equal hand which protects his person and his property; by neither invading the equal rights of any Sect, nor suffering any Sect to invade those of another. ….Because it will destroy that moderation and harmony which the forbearance of our laws to intermeddle with Religion has produced among its several sects. Torrents of blood have been spilt in the old world, by vain attempts of the secular arm, to extinguish Religious discord, by proscribing all difference in Religious opinion. Time has at length revealed the true remedy. Every relaxation of narrow and rigorous policy, wherever it has been tried, has been found to assuage the disease. The American Theatre has exhibited proofs that equal and complete liberty, if it does not wholly eradicate it, sufficiently destroys its malignant influence on the health and prosperity of the State. If with the salutary effects of this system under our own eyes, we begin to contract the bounds of Religious freedom, we know no name that will too severely reproach our folly. At least let warning be taken at the first fruits of the threatened innovation. The very appearance of the Bill has transformed “that Christian forbearance, love and charity,” which of late mutually prevailed, into animosities and jealousies, which may not soon be appeased. What mischiefs may not be dreaded, should this enemy to the public quiet be armed with the force of a law?" – Madison –Memorial and Remonstrance Against Religious Assessments –