Is it okay to preach da'wah or other religions besides a Christian open-air preacher in public?

Imagine you're just a grumpy indonesian gal who wanted to go into my home country. Then on your way to the street, airport or whatever else, you find the same ol' Christian who says things like, "accept Jesus Christ as your lord and saviour before you die", "hell is real" or "embrace the trinity". Y'know, all that kind of jazz.

Would it be acceptable then be okay if I preach Islam doctrine besides her? I mean, I'm not Muslim, but i did spend years on Madrasa. And well, the basic belief should be more or less the same. I could just say things like, "accept Allah before you die" or something like that. I mean, if Christians could do it in airport, so can I, right?