Who Thought That Early Christians Formed Associations?

In the long-standing debate whether or not early Christians formed associations like their non-Christian contemporaries (collegia, 'Greek passage' vel sim.), it has always been taken for granted that this is how they were seen by at least some authors in the second century ad. However, a close investigation of the relevant texts by Pliny, Lucian, Celsus and Tertullian shows that this assumption is in fact unwarranted. The comparison may be fruitful as a scholarly enterprise, but the argument that it was already a preoccupation of ancient observers needs to be abandoned.