Not Faith, But Christ

Our justification is the direct result of our believing the gospel; our
knowledge of our own justification comes from believing God’s promise of
justification to every one who believes these glad tidings. For there is not
only the divine testimony, but there is the promise annexed to it, assuring
eternal life to every one who receives that testimony. There is first, then,
a believed Gospel, and then there is a believed promise. The latter is the
“appropriation,” as it is called; which, after all, is nothing but the
acceptance of the promise which is everywhere coupled with the gospel message.
The believed gospel saves; but it is the believed promise that assures us of
this salvation.

Yet, after all, faith is not our righteousness. It is accounted to us in order
to (eis) righteousness (Rom 4:5), but not as righteousness; for in that case it
would be a work like any other doing of man, and as such would be incompatible
with the righteousness of the Son of God; the “righteousness which is by faith.”
Faith connects us with the righteousness, and is therefore totally distinct from
it. To confound the one with the other is to subvert the whole gospel of the
grace of God. Our act of faith must ever be a separate thing from that which
we believe.

Horatius Bonar, The Everlasting Righteousness