If any one saith, that there is no mortal sin but that of infidelity; or, that grace once received is not lost by any other sin, however grievous and enormous, save by that of infidelity; let him be anathema.
The Protestant is keen to say that nothing a man does is sufficient to cause him to lose salvation, with the (usually heavily qualified) exception of disbelief. As the Council teaches us, this is an error. As we have seen, however, “perseverance of the saints” is itself an unbiblical error; true Christians can lose their salvation.
Nothing in the 27th canon is contrary to the doctrine of justification by grace.