Putin, "What I'm getting at is why can't Rama and Jesus both be manifestations of the same god? Certainly the concept of the trinity allows for one god to appear in multiple forms. Couldn't the trinity be extended to include other forms? "
-There are many reasons, but one of them is because Christ said "“I am the way and the truth and the life. No one comes to the Father except through me." (John 14:6) He didn't add, or someone like me.
But Christianity is not unique in this. Most religions have beliefs that cannot be reconciled with other religious.
"And I echo the question from Orathaic. You earlier claimed god's mind is unknowable, in which case, how can we know that the Christian path to salvation is correct?"
-I don't recall claiming that. We have a limited understanding of his mind. It is given to us through the Bible, and it provides us the path to salvation.
How do "I" know it is correct? By faith: "Now faith is the assurance (the confirmation, [a]the title deed) of the things [we] hope for, being the proof of things [we] do not see and the conviction of their reality [faith perceiving as real fact what is not revealed to the senses]." (Hebrews 11:1)
But, you didn't ask how "I" know it is correct, you asked how "we" know it is correct? To that, I would have to say, it would have to come to each and every one personally like it has to millions of others. You may want to read the bible and see if it comes to you. I would even suggest that you challenge God by praying "If you are the one true God, please reveal yourself to me" before you read it. If he is, how can he deny your challenge? If he isn't you just mumbled a few nonsensical words, before reading a book. No harm done. The book of John is a good place to start.