Is there anyone speak English as their first language?

Hi! I'm writing a short script for my school's play which is going to be performed in English.
I need to get a correction of the two sentences that I've made.
So please help me if you are a native English speaker!!

My sentences are below with quotation marks:
(In a sense of reincarnation)
"I was a Mongolian warrior in my past life."

(Jack is pretty sure that Steve is gay so Jack tells this line to
his friends)
Jack: "I bet five bucks says Steve's gay."

Do those two sentences make sense?
If they seem awkard, could you possibly correct them so that they make more sense?
Especially, the second sentence "I bet five bucks says Steve's gay." -
Can you change it more naturally so that it sound more colloquial?

I'm not a native English speaker but I speak and write it better than most natives.

the first one is ok, but kind of odd since he says with with such utter conviction. How does he know exactly what he was in his past life?? why not a chinese warrior?? lol anyway why would two sentences make such a major difference in your play?? I would suggest you visit www.stageplays.com you might get help from actual playwrights there. :]

the second one, why is he betting on his friends homosexuality?? maybe he wants to say "I think Steve is gay" but if you're going to have a bet why not raise it?? "I bet you $500 that Steve's gay." either post your whole play here or go to stageplays.com otherwise I dont understand why you would ask for help with two measly sentences. cheers! :]

the second sentence is homophobic.you 'd better choose another one

AND THE SUBJECT IS DEPLACED KOREAN MAKE YOUR QUESTION ON THE ENGLISH LANGUAGE FORUM.

C'mon give me a break! Isn't that kind of sentence common in America?

The way Americans talk is usually sarcastic and witty!

The first sentence is correct. The second one should be either "Five bucks says Steve's gay" or "I'll bet five bucks (that) Steve's gay" (you don't need the 'that' unless the speaker is speaking slowly or trying to be clear or something like that).

And it's not homophobic. Leave him alone. It's probably funny.

What Skippy said.