Human’s advent towards civilization introduced rules for society, so that everyone can enjoy certain degree of freedom and peace. From the Neanderthal ages, wild humans became tribal, then grew to religiousness few thousand years ago. A part of the world was caught in wars, might and supremacy while another fraction engaged in spiritual enquiry, investigating why different people behave differently, what bring them to clashes and what would ensure the peace and harmony. Former declared the latter as cowards, while latter declared former as ignorant, wild, and barbarians depending on intensities of their acts. Rishis, in Indian continent, some 3000-5000 BC  elevated to conscious thinking process, possibly got connected to metaphysical world through meditation or deep logical analysis and discovered science of creations, existences, human psychologies, and sociologies. First we called them philosophies, then it became religion, and today we call it Myths. In fact, they are truths, irrespective of whatever name we want to give it. All these while, civilizations co-existed with ignorance and knowledge; some were tribal and some religious and spiritual. This is due to the eternal nature where good and bad co-exist all the time. This entails to two selves within us, the ignorant one is often overpowered by the desires and ego within us, yet the goodness or guilt is realized by the sixth sense within us, called ‘kayastha’ in scriptural concepts. These truths travelled to various parts of world and transformed into different religion, mingled with contemporary norms and culture. Societies fell to impiety and inhumanities, and at various point of time and place, Avatars, Messiah’s, and Prophets came to rescue humanity, thus the religions were born. The moment we start looking at the conceptual understanding of various religions they all look to be the same, and seem to have a common sourcing. Christianity seems to have taken its roots from Kritsna’s diction in Bhakti Yog. Islam is purely based on concepts of formless God, similar to Sankhya-Yog. Buddhism again is Sankhya-Yog, and its Ten Commandments are sourced from Sanatan Dharma, as evident in SBG. Jainism emphasize on compassion and purity, again a part of Sanatan Dharma. Jews have emphasized on individual upgradation and Purushartha that they term as Yeshiva, and several other similarities. Thus, going by chronology of religious developments, world religions – Buddhism, Jainism, Christianity, Islam  seem to  have been carved-out from Sanatan Dharma,  which provides four paths to connect to God owing to various mentalities humans can possibly have. Therefore, all the religions are the same. In fact, these religions were rather the course of history, and not religion as such, because true faith people follow is intrinsic, and it is not bound by the man-made religions we practice. Satwik, Rajasic, and Tamasic characteristics are found in people of all religions.  These psychosomatic factors in nature mould the way people think, believe and act. 
The day this concept is accepted and taught in schools officially, all inter-religious conflicts would end, political biases would go and nations would realize its true potential. However, this would not be possible if fundamentalist stick by the conventional wisdom and religious ego, fuelled by the selfish politicians. This is the chicken and egg story. Unless true logic of religions are popularised, people remain confined by prejudiced mindset and consensus to teach religions as curriculum in schools, would not be possible. The truth is that even in modern world of science and technologies, people are driven by religions and castes, consciously and subconsciously, overtly or covertly, which is evident during elections in the country, and terror incidents, causing unbearable turmoil’s and aftermath. Given no education of religions, countries continue to struggle under presumptive and contemptuous political atmosphere. Humanity has yet to see the most amicable, benevolent and flourishing phase.
Sanatan Dharma provides a complete curriculum, which can be augmented by similar excerpts from other religion’s books to emphasize on their common connections. Analysis of human behaviours, social reconstruction, rise and fall of societies, Purusharth, yagya and Yog’s should be part of the studies. Meditation, that improves brain’s analytical efficiency and renders poise to reactive behaviours, should also be taught to the children to imbue logical thinking, wide perspectives and balanced personalities in them. Science and symbology of Religions, and meaning of Brahm comprising Prakriti, Purusha and its astonishing similarities with quantum  Physics should be discussed in curriculum. Scriptures should be re-interpreted logically, instead of taking them by words, and declaring them as myths and floccinaucinihilipilification.
It is incorrect to think Sanatan Dharma as a typical Hindu religion. It belongs to the entire humanity as it has mothered all the religions of the world, directly or indirectly. There are lot of conceptual similarities among world’s religions, as discussed in previous sections, except the contemporary cultural effects, which are often misconstrued as part of religions, such as dressing, foods, language etc. We are born in prisons of religion and tend to favour the religion we are born in, and un-see the value in other’s. In fact, most never ever go through their religious books, nor it is taught in a very logical way. World is missing such a vital and essential learning. A repository created by thousands of Rishis in thousands of years cannot be discovered by individuals or even an organization.
Principle of Secularity in constitution, seems to be formidable hurdle for organized religious education in schools. Its application needs to be understood. The law can be secular, but education should have all its dimensions and should not be strangulated by such principles. It is the right of humans to learn from the experiences and learning of ancestors, and their directions compiled as religion. Many knowledgeable people contemplated for thousands of years to put it together, which is not possible for an individual in his life time. Secularity got injuncted into constitution due to religious conflicts, which were due to superficial understanding, practices, and political misuse of religions. If common grounds of religions are discussed logically, in school books, and a conceptual understanding of religions can be developed then schism is not expected, and children will grow matured, free from religious biases. Which would unleash the true potential of people and the country. Humans can never be fully irreligious, the day they become so they will be animals again. Hence, it is important to educate religions in schools, logically, and prevent people from being indoctrinated, and inducted into evil, in them name of religion. Conceptual and comparative studies would allow people to learn how humanity evolved with various religions, where our ancestors were coming from while directing humanity, and how it can be taken further with modern knowledge. To this extent secularity should not be a concern, and it should not limit the education. Moreover, broad minded discussion would be possible, which are otherwise sometimes seen as blasphemy. 
In fact, most countries already teach religions in their school, except India. All Christian, Islamic, Jewish and Buddhist nation teach religions in their schools. { http://kssnotes.blogspot.com/ 2018/02/christianity-and-islam-9th-standard.html, http://ollreled.org/grade-8/, http://www.academia.edu/ 4088093/Buddhist_Religion_and_Moral_Education_For_Class_Eight, chrome-extension://ngpampap pnmepgilojfohadhhmbhlaek/captured.html?back=1_}
Even IB curriculum has introduced the course, but at the time of writing this text, the contents focus on the practices, rather than the concepts, and discuss the ills of castes rather than spirituality, that drives egalitarianism, utilitarianism and compassion which is the key pillars in Sanatan Dharma– these should be taught.

Sanatan Dharma was neither given any specific name nor was it directed to one group of people. It was meant to address all categories of humans and bring them onto the path of piety in suitable and acceptable ways.
Ask a driver how the car works, His normal reply would be: Simple! Turn the key, hold steering, press the clutch and press accelerator to move forward. The same question will be answered differently by a mechanical engineering student: Well, there are set of pinions in the gearbox, hooked to the engine shafts, and as the engine ramps up, the cylinders transfer the force to the axle and that makes the wheels run etc... Both are the right answers, but focussed on different aspects. This is the difference in a superficial believer like Bhakti yogi, and the logic learner  Sankhya-Yogi.
Naturally, their responses differ based on the depth of knowledge they possess. Imagine, if the car breaks down, the driver might push it hard to the nearest workshop, while, mechanical engineer might fix the car. The knower of fundamentals could also teach the driver how to maintain his car to avoid a breakdown. Such differences are found in  believers of all religion, but only Sanatan Dharma has recognized it in order to address to all kinds of people.
As the generation is becoming more logical, simple belief system is diverting them away from religions. They deserve to understand the logic of Religion, which books do not discuss. Thinkers (Munis) and Researchers (Rishis) meditated and engaged in Shastrarth (like paper presentations) to discover nature, and about the solutions to the threats Humanity faced. Today countries have problems for which their people are struggling for the solution. We tend to copy solutions from the countries who do not face similar problems. Customized solutions to our needs would require structured thinking with unbiased groups. I asked several foreigners what they think about India. The majority of the answer were, that India has too much population, and too much politics and everything is done by Ganesha not people. I was astonished to see that their responses were quite true, in fact. But they do not have similar problem. So we cannot copy solutions from them, as we often doo, instead we will have to discover our solutions. We were the pioneers of knowledge and we can be again. Once world agrees, that all religions are brothers and relatives, with no conceptual, but cultural differences only, we will be able to solve political problems and terrorism. 
Sanatan Dharma, logically seen, is a completely secular and scientific doctrine. While based on eternal principles, it applies to all irrespective of their caste, creed, religions, country and any geopolitical origin and even to animals. Sanatan Dharma holistically synchronizes these components in complete harmony, deriving the best of every component for everyone. We must understand the need for logical teaching of religions in schools, to help direct humanity in right directions.