The cross was a feared instrument of Roman torture and punishment. Were people repulsed or perhaps shocked when this new group started using it as one of its key symbols?
Interestingly, early Christian visual art didn't use the cross as a symbol. Christograms and other kinds of images (the Good Shepherd, for example) were common, as were significant, typological scenes from the Hebrew Bible. The cross didn't become a prominent marker of identity in visual art until after the time of Constantine.
Spier, Jeffrey. Picturing the Bible: The Earliest Christian Art. New Haven: Yale University Press, 2007. Print.