In that email, ensure that is nice, brief and polite, and ask for 4 things: 

ONE
Identify that you are from their electorate. Put your contact details (including your street address) in the email so they can respond. Anonymous and emails from outside their electorate are usually ignored.

Find your local MP

TWO 
Compliment your MP. They don’t get a lot of encouragement so encourage them. 

THREE
Ask for a ‘Federal Religious Discrimination Bill’ – please use those four words. 

FOUR
Then use this phrase ‘People of faith must not be worse off because of this Bill’. The reason why you are using those words is that the Prime Minister has made that promise. 

End the email politely.