Those six people in the poem had discriminatory attitude towards others, and that is why they did not share their logs to keep the fire burning. Those people had better risen above their narrow considerations of class, caste, colour, race, religion and ethnicity to make friends with each other and share their woods to the fire to keep themselves alive. That is the message the poet wants to deliver.
 
Now read here what would have happened if one of them had offered his log to the fire.