The Religious freedom that is spoken of in the Constitution is how it becomes possible to have a free and dynamic country using small Government.
A person who believes in God, sees something that is larger than themselves and man. This means one is required to have more self control, since God is omnipresent and omniscience. The godless only have to check their compulsions, if another human is watching. But under the cloak of darkness, you can do what you want. The religious does not have these same hiding places, because of an all seeing God; fewer crimes.
For example, if there was a speed limit on a road and you knew there was police nearby, you will not speed. But if you knew all the police were at a large fire, and there is nobody to catch you, many will speed. The religious will have a harder time justifying this, since they know God is still watching. So you need fewer police to catch speeders if all believed in God; smaller government.
No religion teaches people to be mean or to be greedy since both of these are considered cardinal sins. The Godless are not under these same rules, since they have relative morality and can justify anything. Now you need more people to make it fair; Big Government.
The Seven Cardinal Sins
The seven deadly sins, also called the seven capital sins or the seven cardinal sins, in Roman Catholic theology, are the seven vices that spur other sins and further immoral behaviour. First enumerated by Pope Gregory I (the Great) in the 6th century and elaborated in the 13th century by St. Thomas Aquinas, they are (1) vainglory, or pride, (2) greed, or covetousness, (3) lust, or inordinate or illicit sexual desire, (4) envy, (5) gluttony, which is usually understood to include drunkenness, (6) wrath, or anger, and (7) sloth. Each of these can be overcome with the seven corresponding virtues of (1) humility, (2) charity, (3) chastity, (4) gratitude, (5) temperance, (6) patience, and (7) diligence.
Say you were an Atheist and decided these cardinal sins; trigger sins, are old wives tales, so you will decide you will do the opposite to spite the religious. We will need much more government to mop up the mess. The believer is taught to check these seven behavior and try to avoid these impulses, since they tend to lead to deeper problems, that will require larger government to mop it up.
The homeless drug addiction problem is rooted in gluttony and sloth. These are fairly minor offenses on the surface, but these capital sins, can lead to a bigger social problem, since any of the cardinal sins can spur other sins; greed and anger; drug crime. Now we need even more government.
Bigger Government is symptomatic of compounding social problems, caused by not avoiding the base or cardinal sins, that can spread to even worse things. Lust now requires surgical removal of genitals; sex reassignment and new government program. The Religious freedom was there so people could reverse this and thereby get by with much less Government. Since Government wants to grow; via pride and greed, the founders made sure that government could not establish any religion. Pride and greed would add sin as an excuse to grow and exceed its role; swamp.