good blog post from Desiring God here’s just a bit:
So the good news of what it means to be “in Christ” must be combined with the good news of how one can be “in Christ.” Spirit-granted faith is the means that brings us into the glorious reality of union with Jesus. Faith is not the end and it is not our hope. Faith is the embracing, not the thing that is itself embraced.
Calvin says it this way in Institutes III.XI.7,
We compare faith to a kind of vessel; for unless we come empty and with the mouth of our soul open to seek Christ’s grace, we are not capable of receiving Christ. From this it is to be inferred that, in teaching that before his righteousness is received Christ is received in faith, we do not take the power of justifying away from Christ.
read the whole thing here