Well, from a more pragmatic point of view, how many of those that you preach the Gospel to are actually saved? If you believe that all are eventally saved, then I agree with you completely.
But, if instead, only a small portion of those that hear actually heed the call, I would say you are doing a disservice. Am I condemning more than I am saving??? The Bible seems to imply that a minority are saved:
Matthew 7:13-14
13 "Enter through the narrow gate; for the gate is wide and the way is broad that leads to destruction, and there are many who enter through it. 14 "For the gate is small and the way is narrow that leads to life, and there are few who find it.
You are assuming that they are not liable for the light that they do have.
Romans one says they are.
Therefore, they have zero chance before the preaching of Christ, and they have a real chance after the preaching of Christ.