What does make something a religion though? If you think about it, ideologies have traits of religion, they have value systems, doctrines, a view of morality and a perspective on how society should be organized. One could argue that the addition of a supernatural being as central to the ideology elevates a mere system of thought to a religious system of thought. However, given that we have religions without supernatural beings, such a various pagan religions where gods are merely representations of mother earth or the starts (very natural things) in anthropomorphic forms.
Scientology is classified as a religion, but to my knowledge the “supernatural” beings of that particular belief system happen to be natural beings with advanced technology. So, it would seem that belief in a deity does not a religion make.
If we compare the definitions of ideology  and religion 
(plural ideologies) A system of ideas and ideals, especially one that forms the basis of economic or political theory and policy: the ideology of republicanism
The belief in and worship of a superhuman controlling power, especially a personal God or gods:
A particular system of faith and worship: the world’s great religions.
In the case of the latter, I dismissed the first definition as I’ve already made the argument that a religion does not hinge on a supernatural power.
In the case of the definition of ideology, it puts particular emphasis on economics, political theory and policy. In the case of religion, it puts emphasis on “faith” and “worship”
Faith  is defined as:
Complete trust or confidence in someone or something: this restores one’s faith in politicians
And worship  as
Adoration or devotion comparable to religious homage, shown toward a person or principle: our society’s worship of teenagers
So we can clarify the definition of religion as:
A particular system of complete trust or confidence and adoration or devotion shown to a person or principle.
This does not change the meaning of the definition it mere expands on it in order to make it more complete.
From these definitions we can argue that an ideology transforms into a religion when its believers show complete trust, confidence, adoration and devotion to it.
From the preceding argument it follows that any ideology could to some or many become a religion rather than an ideology.
The when it is your religion, when it is your preferred ideology?
I’m a big fan of capitalism, is it my ideology?
Do I show complete trust in it?
I suppose as always that this would depend on the definition of “complete trust” if we define “complete trust” in that I have faith in that it can solve all problems, that would be a no.
Am I completely confident that capitalism can always work for the best possible end?
Again, this depends on what the end is. Optimal allocation of resources from a pragmatic perspective? Probably. Optimal allocation of resources while ensuring the least necessary harm? Not so much. Capitalism is a tool, and just like many other tools, using a wrench to hammer in a nail and a hammer to tighten a nut, does not work very well.
Do I show adoration for it?
I do have a thing for capitalism, but I do see other ideologies on the side. There are aspects of socialism that can be beneficial in certain periods, such as Keynesian intervention in downward market, or times where the good of a country must be put before the good of industry, such as times of war.
Do I show complete devotion to it?
Again, I do see other ideologies on the side, and there are many variants on capitalism, ranging from laissez-faire capitalism to state capitalism and to social democracy. Can capitalism provide the answer to all of life’s problems? Considering that if left unchecked, capitalism focuses on breast enlargements, boner pills and treatments over cures, I’d say no. It’s not in the financial interest of a company or companies to develop cures over “take 3 of these every day for the rest of your life“.
I think the exercise above is the correct way to determine whether you are treating an ideology as a religion or as a system of thought with flaws, problems and errors. All systems of thought we know are man-made, all men have flaws, thus it follows that all man-made systems have flaws.
I’m reminded of a quote frequently attributed to Winston Churchill:
“Democracy is the worst form of government, except for all the others.“
To deal with some of them, if you restrict the vote, not everyone is represented, and thus you do not have a true rule of the people, you have a rule by some people. Which makes it equivalent to “all the others”. On the other hand, if you give the vote to everyone, then it is the equivalent of asking your cardiologist, your accountant, your lawyer and your babysitter to come up with the best way to deal with your car being broken down.
Can we expect the order to arise from chaos? Can we expect individual competence to arise from collective incompetence? Can we expect a population that is not well educated renaissance men to know enough of the various fields of knowledge that intersect in what we call government?
How much is fact and how much is opinion? This was one of the cornerstones of my education in economics, “Economists do not make value judgements, we compare 2 or more scenarios and tell you the likely results, without saying anything about which result is the most moral, or most beautiful.”
I suppose this could be perceived as a digression from the argument and subject-matter at hand, but it is precisely the moment where you seize to be able to evaluate a system of thought based on cold, hard logic and facts, and mix morality and other soft-values into it, things become religion.
There are degree to it of course, but to bring it back to the picture that leads into this post: Once a person crosses the river into a land where no argument and no fact could convince them that they are not 100% right in their beliefs, they have adopted a religion. Once they admit no flaw in their adopted system of thought, they view it as a religion.