My girlfriend and I will be travelling from Cincinnati to Athens, Greece in the next few months. There will be a stop on the way to Athens at CDG in Paris. I'm assuming that I will have to pass through customs once arriving at CDG. However, my layover there is only 1 hour. Is this enough time to pass through customs and board my connecting flight?
One hour can be really short, even if there are no delays on your flight from Cincinnati.
As a precaution, before landing in Paris, notify the flight attendant of the situation; tell them what is your next flight (number and destination) and ask them if they know what gate is your next flight, and if it is in the same terminal.
It might be possible that they will let you exit the plane before other passengers.
Remember, DON'T PANIC.
Anecdotal, the last time we went through CdG (from Montréal to Italy,2 3 years ago), it was a short layover and we were stuck at one checkpoint because they were understaffed; we ran like hell after that.
I lost a layover in CDG having only 50 minutes to do it. Even though the first flight didn't arrive late, I got help passing fast through immigration (the staff came to help me while I was in the line) and I ran. The flight was Santiago (Chile) -> CDG -> Amsterdam. All flights operated by the alliance Air France - KLM.
That time Air France just gave me a seat in the next flight to Amsterdam.
Nowadays I no longer take such shorts layovers in CDG.
If possible, pay for a seat in the front of the plane in the flight Cincinnati to CDG and travel with basic hand luggage.