In our justification, faith is the means by which we are linked to Christ and receive the benefits of his saving work. By faith we receive the transfer or imputation of the righteousness of Christ. Faith is not only a necessary condition, it is a sufficuent condition for Christ’s righteousness to be imputed to us. Faith, true faith, is all that is required to be justified by the righteosness of Christ. Faith trusts in and lays hold of a righteousness that is not our own.
Sproul, R.C.; Grace Unknown: The Heart of Reformed Theology; Baker Books; Grand Rapids, MI; copyright 1997; p. 66-67