From this month's Gerhard translation work. The forthcoming volume On Justification is a must read. So many of our contemporary questions, especially regarding the Antinomian/Radical Grace strains within today's Lutheranism and wider Evangelicalism, are dealt with in fine detail.

Bellarmine [Gehard's Roman Catholic opponent....seeing in advance the ground that the Radical Grace folks would tred] retorts: “If faith, separated from the other virtues, were able to justify, it could also do this in company with the vices which are contrary to the virtues. After all, as the presence of the other virtues does not benefit faith for the work of justifying, the presence of vices will not hinder it, because they are connected with it accidentally as are the virtues.”
       We respond. The word “alone” has to do with the predicate. Faith, to the extent that it justifies, alone accompanies this act. Meanwhile, justifying faith is not alone; much less does it exist with vices, that is, with sins against conscience. How, then, would it justify with vices? Acting presupposes being; but faith does not exist with vices; therefore it does not justify with vices. Faith separated from virtues does not justify because it does not exist without virtues. Yet still it does not communicate the power to justify to the virtues and this [faith] alone justifies.

And a little more...Radical Grace has always been how Calvinists like to describe "once saved, always saved." It's not Lutheran.

 [Bellarmine] brings this forth from Calvin: “the seed of faith remains amid the most serious lapses.”
We respond that the Augsburg Confession (Art. 12) explains our opinion clearly against the Anabaptists, that “once justified, people can lose the Holy Spirit,” namely, through sins against conscience. Therefore justifying faith and sin that attacks it cannot stand together at the same time.

+HRC