Christians are called to spread the Gospel. We are not called to argue about its veracity. The Gospel message is perfect and it saves imperfect people - and we are all imperfect - who confess Jesus Christ as Savior and Lord.
We speak. God changes the heart.
The responsibility for the argument is upon the one who wants to argue. I leave the 'people of the earth' to their own devices.
Become the kind of person that when your feet hit the floor in the morning, Satan groans and says, "OH CRAP, HE'S AWAKE".