The court case in California challenging the teaching of Yoga in schools helps show the theological underpinnings of "secularism".
See here.
See here.
Many people have come to think the secular can be a neutral space for co-existence within a plural society. Such a construal misses the theological underpinning of the ‘secular’. In The Heathen in his Blindness, Balagangadhara further shows how the distinction between the religious and secular is drawn by and within a religion. Within such a theological framework, the secular is a zone where practices of a false religion, cleansed of its idolatrous practices, are assigned as an alternative to assigning it to the place of true religion. Perhaps those enunciating ‘Christian yoga’ are engaged in doing the latter, as Rajiv Malhotra’s discussion of the trend indicates. That is, they are engaged in purifying it for Christians to adopt as a religious practice. Judge Meyer in Sedlock appears to have done the former, ostensibly persuaded by the carefully calculated arguments submitted by the defendants that the yoga classes had had the cultural and religious elements removed from them, with the names for various asanas having been substituted with other terms, and Sanskrit terms and mantras having been dropped.