The Belgic Confession (BC) Article 22 is clear that faith is the instrument by which we appropriate what God has given the elect.
Here’s the Belgic,
“It is, therefore, a terrible blasphemy to assert that Christ is not sufficient, but that something else is needed besides Him; for the conclusion would then be that Christ is only half a Savior.
Therefore we rightly say with Paul that we are justified by faith alone, or by faith apart from works of law (Rom 3:28).4 Meanwhile, strictly speaking, we do not mean that faith as such justifies us,5 for faith is only the instrument by which we embrace Christ our righteousness; He imputes to us all His merits and as many holy works as He has done for us and in our place.6 Therefore Jesus Christ is our righteousness, and faith is the instrument that keeps us with Him in the communion of all His benefits. When those benefits have become ours, they are more than sufficient to acquit us of our sins.” (1)
Murray is helpful here,
“…in the Scriptures, justification is never said to be dia pistin (on account of faith).”
“God does not justify us because of our faith, he justifies us because of Christ, and we just happen to receive that through faith.” -Horton