Do good works always express saving faith in Christ, even when that faith is not explicit?

Question

My understanding of the Catholic view on the relationship between faith and works is that faith and works are inseparable. Which is to say that true faith will always find expression in works, and that every good work is automatically an expression of faith. (And as such every good work leads to an increase in justification, because it demonstrates an increase in faith)

I'd like to hone in on the second part of that equation in this question: "Every good work is automatically an expression of faith." Does this hold true for people who are completely ignorant of Christ? For example if a Muslim in Saudi Arabia who has no knowledge of Christianity performs a truly good work, does that work demonstrate implicit faith in Christ?

Just to clarify the example:

1. The Muslim may have a totally warped view of Christianity and actually believe that accepting Christ is a heretical action/mortal sin according to Islam. So they would be explicitly denying Christ with their beliefs while implicitly demonstrating an acceptance of Christ with their actions.
2. By "truly good work" I'm talking about a work which truly demonstrates Christian charity. Not a work which merely appears to be good or is actually self-righteous. I'm talking about a genuinely good work which is pleasing to God. One which totally fulfils the great commandment to "Love your neighbour as yourself"
3. If it's the case that the Muslim demonstrates implicit faith in Christ by their good work despite explicitly rejecting Christ in their beliefs, this would lead to an increase in Justification, just as it would for a Christian.

Consequences if it is true that good works always demonstrate saving faith: It is possible to demonstrate saving faith in Christ in your actions whilst explicitly rejecting him in your mind.

To restate the question: Does the phrase Every good work is automatically an expression of faith mean that non-Christians can demonstrate saving faith through their loving works without even realising it?

Answer 1

Distinguo Sanctifiying grace is the grace freely given by God which saves us and it doesn't come in bushels or pecks

According to the Council of Trent sanctifying grace is not merely a formal cause, but "the only formal cause" (unica causa formalis) of our justification.

old catholic encyclopedia - justification

Actual Grace is the spiritual grease that tunes your soul into being better and better. So, corporal and spiritual works of mercy are not the cause of salvation. They help you stick to the narrow path, but they aren't the narrow path.

What I do not know, and prehaps only God knows, is what good acts of mercy do to the soul of the one who doesn't believe in Christ.