A religion acts as a reliable vessel for an important message (truth) to pass along the line of humanity. The method employed to pass such a message is called human witnessing. This is the most efficient way for a truth to be conveyed among humans as long as God has a strong reason not to show up to humans in majority. There's no other way round.
1. Not all religions have a strong reason for their gods to hide behind. If a god is much more superior than humans and he cares about humans he should show up publicly to guide humans.
The strong reason for the Christian God to hide behind is that all humans are bound to a covenant which everyone requires faith in order to be saved. God shows up to everyone simultaneously means no one can be saved.
On the other hand, if God doesn't show up to anyone, then no humans can get to know who God is. No humans can know what are God's requirements set forth for humans to follow.
The only way which works for a hiding God to make Himself known to humans, to make His requirements known to humans is to show Himself up to a small group of direct witnesses (explicitly His prophets and chosen witnesses), and for them to write about Him and what He wants then for others (humans in majority) to believe or not.
There's no other way round for such a truth to be conveyed.
2. Now which God can explicitly name this method of conveying truth?
Multiple accounts of witnessing, witnesses, prophets being explicit called God's witnesses, emphasizing on no false witnessing allowed, these are all unique characteristics of Christianity.
No other gods can be true in this perspective.
Moreover, no witnessing can be made more valid than those who martyred themselves for what is said and done. Today we have photos and videos in supporting our witnessing though.
What matters is not who claimed the deity, what matters is how the claimed deity chose to convey his messages deemed important. He's conveying in an efficient way humans can't think of, plus that there's no better way round for such messages to conveyed, then He's God.