Lo naturale è sempre sanza errore, ma l’altro puote errar per malo obietto o per troppo o per poco di vigore. The natural is always without error, but the other may err through an evil object or through too much or too little vigor. —Dante, Purgatorio, Canto 17, 94-96
Nothing in this rebuttal depends on the meaning of is. If God is love, the inference goes through with the copula being interpreted as a relation of identity, predication, or belonging. It might be argued that in loving God man runs the risk of not being loved in return, in the event of His non-existence. But it is implausible that love—unlike its collateral attitudes such as fear—could be predicated without presupposing the existence of the lover and the beloved alike. There is something wrong with our homiletic premisses. Love does not require the risk of not being loved in return. Or else, God is something other than love.