This would have been my response...

Dear friend,

I do not know you, where you are from, nor your actual motivation in wanting to engage in this “talk” with me. I am not sure what made you pick me to talk with you but I am not interested to talk on religions. I am even less interested to convince you on the truth of Buddhism. If I were to do that, I will be a shame to all Buddhists. Anyway, I do not have the time for such talks which brings nothing but pride and ego. And this is the very thing that the Buddha taught to avoid. Everything is impermanent. So is human life. Very soon this fragile life will come to pass and I do not wish to regret living but not helping my fellow inhabitants of this world who are in need. And there are so many people in this world who are in need of a helping hand… or just a simple smile. I cannot look forward to be Paradise and rest there in peace nor enjoy the happiness there knowing that others are still wallowing in suffering and pain. I cannot afford to waste my precious time in non-beneficial comparisons.

Therefore, please do me a favour. Help the people around you as much as you can. Relieve them of their pain and problems. Bring them happiness. Cultivate in them harmony and peacefulness to live together despite the differences in race, nationality, religion, etc. Make them love each other. Love me. Love yourself. You should commit yourself to this work in helping to make this world a better place to live in. Are you willing to do that?

In the meantime, I make my humble respect to you! I wish you and all your family every happiness and success in this world and thereafter!

With one heart bowing,

A buddhist

Comment:
...No, but I do not intent to send this reply to him. Buddhas do not push dharma "down sentient being's throat". They will "choke". If sentient beings do not have the karma to understand the Buddha's teachings, it could possibly even be detrimental. So, Buddhas will wait for better opportunity.