Add to that a wholescale review of the political governance process, such as removing the House of Lords, disestablishing to C of E ...
In my argument against the monarchy I deliberately steered clear of the whole establish church element, specifically because this is a problem with our monarchy, not a problem will all monarchies. It is perfectly possible to have a constitutional monarchy without any established religion and with no link to any particular religion.
However in our case there is the compounding issue with the established church, so for the UK specifically there are some additional problems/arguments against, such as:
1. Fundament right to freedom of religion, including the freedom not to be religious and to change one's religion. If the monarch is head of an established church that is fundamentally contradictory to freedom of religion on an individual basis.
2. Equal status for all subjects/citizens - if the head of state also clearly favours a particular religion, which is therefore established some subjects/citizens have a poorer status than others on the basis of their religion.
Hence the problem with Defender of the Faith - defending it against who? Presumably those who hold a different faith. Charles ties himself up in knots over this and potentially makes it worse, through his Defender of Faiths or Defender of all Faiths. I cannot accept Defender of the Faith may simply be seen as some anachronistic tradition that those of other faiths and none (presumably those who are the threat that needs defending). But changing this to, in effect place about half the country (those who may claim to have a faith) as needing defending, presumably agains the other half who do not have a faith is divisive, deliberately divisive and unnecessarily divisive.