I honestly don't understand the negative reaction. Religions advertise. In doing so, they are asserting 1) the existence of a (their) god or gods and 2) that their group has at least one true set of beliefs and practices relating to that god or gods. These are truth assertions in the form of "there is an 'X' and our group has true knowledge about 'X'." They also often, if not usually contain the explicit or implicit assertion that joining their group or at least sharing their beliefs will confer some benefit on those to whom the assertion is aimed.
Now, it so happens that many (again, if not most) religions contain as part of their set of beliefs the assertion that their views regarding their god or gods are the only correct, i.e. true ones. So almost any assertion of religious faith -- even the mildest form -- is likely to offend some other religious person's "core beliefs," isn't it, since the "A" group making assertions about their religion will conflict with the beliefs of the "B" group? If that is the case, and giving religious offense is to be avoided, shall we prohibit any public assertion of religious belief?