One's believing does not cause salvation, instead, it comes as a result of salvation.
Consider the following:
1Cor15:1-2 (in the "resurrection" chapter) -
Moreover, brethren, I [Paul]
declare unto you
the gospel which I preached unto you, which
also ye have received, and wherein ye stand;
By [/BY MEANS OF] which also ye are saved [...]" (i.e. by means of the gospel Paul
declared--
no one is suggesting we are "saving ourselves/themselves")
(the rest of the passage spelling out
the vital aspect of "His resurrection"...
and speaks of "your faith" 2x--verses 14,17--speaking of the fact that "
IF Christ be NOT RAISED / be NOT RISEN"--
some did not believe in "resurrection of the dead"--[He WAS / DID though! (the point of this text)],
"your faith" ['the faith OF YOU'] "is in vain, you are still in your sins" [making the point about the vital aspect of His resurrection...
NOT making the point that
"your faith" [/'the faith OF YOU']" is unrequired]).
I'm just (here) making the point that Scripture itself speaks of "
THY faith," of "
YOUR faith," of "
THEIR faith"
(and "
THE faith" which is "
THAT BODY OF TRUTH" found in written scripture
following [
and concerning also] His death / burial / resurrection / exaltation, which we aren't discussing here, exactly)...
...and that these contexts need to be examined also.
Here's a sample LISTING (there may be others):
"thy faith" -
Matt9:22
Matt15:28
Mk5:34
Mk10:52
Lk7:50
Lk8:48
Lk17:19
Lk18:42
Lk22:32
Phm1:6 [,1:5]
"your faith" -
Mk9:29
Rom1:8
1Cor15:14,17 [my example at top of this post]
2Cor1:24
Eph1:15 [in the context of our previous convo]
Phil2:17
Col1:4
Col2:5
1Th1:8
1Th3:5,6,7 [,10]
2Th1:3
Jam1:3
1Pet1:7,9,21
"their faith" -
Matt9:2
Mk2:5
Lk5:20
Phm1:5