Heißt schon so - wenn man niest, hört man zwar auch ab und zu ein 'bless you' (ohne Gott), aber das heißt ja nicht, dass es nur 'Gesundheit' heißen kann.

The Lord be with you
May the Lord be with you
God be with you

Noch ein paar Beispiele

Thomas' second suggestions are correct.
"God bless you" bedeutet anderseits "Gott segne dich" oder eben "Gesundheit!" nach dem Niesen.

May the Lord watch over you. (i.e. "schuetzen" im Sinne eines Schuetzengels)

May the Lord be your guardian. (again, as in guardian angel)

May the Lord protect you.

These variations all have a respectable number of hits in Google. (With guardian, is the more common version, The Lord is my guardian, which is an alternate translation for Psalm 23, The Lord is my shepherd.)

"God bless you" (or more commonly simply "Bless you") is the common response to a sneeze, but is also used in other contexts in which it is to be taken more seriously as a religous expression.