Is 2 hours enough for a connection at ATL?

Yes, 2 hours is plenty for most connections at ATL (Hartsfield-Jackson Atlanta). ATL is actually one of the best-designed airports for connections, despite being the busiest in the world. All domestic terminals (T, A, B, C, D) are connected by the Plane Train, an automated people mover that runs every 2 minutes.

The maximum travel time between the most distant gates (T gates to E gates for international) is about 20 minutes including the train ride. For domestic-to-domestic connections, you're usually looking at 10-15 minutes gate-to-gate. Delta, which operates the vast majority of ATL flights, is highly optimized for connections here.

The only scenario where 2 hours gets tight is international arrivals connecting to domestic flights, where you'll go through customs in the F/E concourse area first. Even then, ATL processes customs relatively quickly compared to JFK or MIA. The airline MCT at ATL is 55 minutes domestic and 120 minutes international, so 2 hours gives you a comfortable buffer for domestic and meets the minimum for international.