Lets go through that passage and see whose faith justifies. It is obviously the faith of Christ. How does one receive the faith of Christ? Believe the gospel of Jesus Christ. The believer is justified by the faith of Jesus Christ.
22 But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.
23 But before faith came, we were kept under the law, shut up unto the faith which should afterwards be revealed.
24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.
25 But after that faith is come, we are no longer under a schoolmaster.
22 But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.
23 But before faith came, we were kept under the law, shut up unto the faith which should afterwards be revealed.
24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.
25 But after that faith is come, we are no longer under a schoolmaster.
If you hold to it being the faith of Christ Jesus that saves then you have to hold to universalism.
Joh 12:32 And I, if I am lifted up from the earth, will draw all peoples to Myself."
So if it is Christ Jesus' faith that saves and He draws all people to Himself that means all people will be saved. That is why your view is errant. It is our faith in the faithful one that saves