Didn't I already suggest you do a word study of how often Scripture speaks of the "faith OF Christ?"
However, here is a source that will answer your question quite well:
http://www.mountainretreatorg.net/bible/faith_of_christ_or_faith_in_christ.shtml
That article is one heck of a botch up of what "faith" basically is.
It is just as off as to what "the faith of Christ" is a reference to.
I suppose God gives the unbelieving the faith to believe against Him.
Faith is simply deciding to believe in a thing and or in a thing as true.
You walk up to a Park bench on a warm summer's day in your belief that it will bring you rest, or whatever; and that that your legs will get you there; and that you have a right to be there; and so on.
All "matters of faith" exercised.
You get there only to find a "Wet Paint" sign on this very shiny bench.
"Having once believed" what "Wet" and "Paint" refer to when together in that way - especially on a park bench! - you exercise your ability to exercise faith in a thing as true or not true, and move on.
Of course, the more astute might pause to "test the things that differ" given that past experience has "led you to believe" that "sometimes such a sign is no longer needed; the paint on this bench might already be dry..."
You did all that - do all those kinds of things - all - day - long - "on faith."
Some assemblies have these huge signs perched up high above their building.
A sign just as simple as that "Wet Paint" sign on that park bench - "Christ Died For Your Sins."
"All men" who read it decide to exercise their ability to form beliefs either in favor of, or against, a thing.
The Apostle Paul's sign reads...
1 Timothy 1:15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners...
In other words "the words on this sign - that Christ Jesus came into the world to save sinners - is true; it is worth believing in.
But when it comes to religion, all of a sudden free will goes out the window.
In its place?
A serious case of "automaton-nigh-tiss."
That is, when it is not that and or "well God gave me a sign the park bench was wet."
In this, most Believers remain "Charismatic" pagans in their understanding of these things.
Even the Apostle Paul himself was going back and forth with Believers on the need to - quit - complicating - the - simplicity of - the gospel - of - Christ.
1 Corinthians 12:2 Ye know that ye were Gentiles, carried away unto these dumb idols, even as ye were led.
1 Corinthians 15:3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; 15:4 And that he was buried, and that he rose again the third day according to the scriptures:
Wet Paint dead ahead...