Fundamental Rights
No person shall be compelled to pay any taxes, the proceeds of which are specifically appropriated in payment of expenses for the promotion or maintenance of any particular religion or religious denomination.
The government cannot create a tax specifically to fund one particular religion. This keeps the state's finances religiously neutral - general taxes that incidentally benefit religious institutions among many other beneficiaries (like general grants for heritage upkeep) are treated differently from a tax earmarked for one religion.
A specific cess or tax collected solely to fund the upkeep of temples/mosques/churches of one particular religion would violate Article 27 - general secular welfare spending that happens to include heritage sites of multiple religions does not.