Originally Posted by
lhrpete
Yes, you will be leaving the Schengen Area at ATH.
...so, you'll arrive at ATH in the same way a domestic passenger would - no passport formalities. I assume from your profile you are a US citizen and so must have a Shengen visa. This covers you to enter Greece from Spain with no passport check. You will then have to leave the secure area, go upstairs and clear passport control (and security) to leave Schengen for your TLV flight. There are no airside transfers between the two areas at ATH unfortunately.