Many of your readings have focused on the Christian tradition in itself. However, Christian faith is always in context. Newbigin's The Gospel in a Pluralist Society has focused on the Christian faith against the backdrop of modern secularity. Ellul and Work have focused in their own ways on the distinctiveness of apostolic Christianity over against both secularity and the cultural Christianity that has made its peace with secularity. You have also read Shermer or Mencken, who describe the Christian faith (actually 'religion' in general) as it appears from that secular perspective, whose many forms dominate western intellectual circles.
You are very likely to take part in this conversation for the rest of your life.
As a group, choose ahead of time two of the most plausible or compelling claims in Shermer or Mencken that seem to undermine the Christian faith. In a chat, examine what response the church offers, or ought to offer, to each claim. (That 'response' might be an argument in defense, an action, a concession, a refusal of the presuppositions of the claim and a radical alternative, or some combination.)
I suggest that one in your group contend for Shermer's or Mencken's claim, another focus on Ellul or Work, and a third on Newbigin. That will help make sure that your group takes all these voices seriously. However, any of you can take any position, including of course positions unrepresented in our readings.
The usual rules apply.