I did quote it, but I do not accept your interpretation of the statement.
It is saying that they give a grounding in Christianity, but not just Christianity.
I also quoted this.
"Many church schools (both VC and VA, primary and secondary) have a high proportion of Muslim children, a substantial number have over 80 per cent intake from the Muslim community."

Would that happen if Christian indoctrination was going on?
That is objective evidence, as is the inspection reports, as are the league table results.