For what I received I passed on to you as of first importance: that Christ died for our sins according to the Scriptures...
1 Corinthians 15:3
I'm enjoying doing Romans for my Summer Bible Study. 51 have joined me! I've taught this book many times. And, as a result, studied and re-studied it over the decades. And, several years ago, I preached verse-by-verse through Romans, over a period of almost two years!
In Romans a number of big biblical themes come forth. Such as the cross, and atonement. And, of course, salvation.
These are particularly important themes for such a time as this, because "progressive" Christians are denying historical, orthodox views of atonement. Many are universalists, and say postmodern things like "Jesus died on a cross, not to pay for our sins, but to 'speak truth to power'." (E.g., progressivists like Rob Bell and William Paul Young, et. al.)
If you are interested in digging deep, check these out.
The Nature of the Atonement: Four Views (essays and responses by Greg Boyd, Joel Green, Bruce Reichenbach, and Thomas Schreiner). I learn much from reading the "Views" books!
What Did the Cross Accomplish: A Conversation About the Atonement, by N. T. Wright and Simon Gathercole (who both hold a variant of penal substitution)
Atonement and the Death of Christ: An Exegetical, Historical, and Philosophical Explanation, by William Lane Craig. (Penal substitution theory [the bane of progressives!])