In other words, say both Allah and Krishna exist. Would both Muslims and Hindus be right? Well, not really. Many Muslims claim that Allah is the only god, so they would be partially wrong. Hindus may acknowledge the existence of various gods, but would reject the notion that the Qur'an is the ultimate and complete word from god. And if either of these gods exist, then atheists did not have a correct view of the world either, because they didn't believe in any gods yet all gods do exist.
And if a subset of Christians claims that only Jesus can lead to salvation, but it turns out that the Noble Eightfold Path of Buddhism can lead to salvation too, then this subset was partially incorrect.
Basically, because many religions (and non-religious philosophies) make objective claims regarding the universe, and a lot of them logically contradict, they inevitably cannot all be correct. Some will inevitably be more or less accurate than others.
But they could all be right. Krishna/Allah could be the same and just a means of communicating a fundamental truth. If you believe in the salvation through Jesus, then it is the only way, unless you follow the Eightfold path which is the way. And those who do not need salvation and do not believe in afterlife just cease. May be we can all be a little wrong and all be a little right. I dunno. Just thinking.....