The trouble is that I've heard it from two people I deeply respect. I doubt either meant it this way, buy the phrase itself shows a profound ignorance of both Heaven and Earth.
For a detailed look at what the Bible teaches about Heaven, I'd recommend Heaven by Randy Alcorn. As for Earth, I only have direct experience of a tiny bit of it, but I've read enough that I think I can speculate a little about the rest.
This world and this life are real, but they're temporary. All that we accomplish here will one day end. Even if you influence millions, one day those millions won't be here. Do you think David Brainerd cares that his biography is still inspiring missionaries almost 300 years later? Possibly, but probably not as much as you think.
Why then do we as Christians get so caught up in the pursuits of this world? I think we've bought into the lie that this world is all there is, that we have to make our mark here, and that anyone who doesn't share our obsessions, which are by and large identical to those of the non-Christians around us, as "so heavenly-minded they're no earthly good".
I know where the phrase came from. It was originally applied to those fundamentalists who so strongly believed that that the next life was what mattered that they thought anything done to prolong this one, even feeding the hungry, was at best a wasted effort.
But that's not what Jesus did. He told the story of the Good Samaritan. He taught the people, but he also fed them. He preached the Kingdom and healed the sick.
I hope I can be a fraction as heavenly-minded and earthly good as Jesus Christ.
