Final answer:
Atticus is concerned that the cumulative injustices faced by Tom and the African-American community will lead to negative consequences in the future.
Step-by-step explanation:
In Atticus' statement, he expresses concern about the future consequences of the injustices faced by Tom and the African-American community. He says that all of these injustices are adding up, and eventually, there will come a time when we have to pay the bill for them. He hopes that this payment doesn't happen during the time of the younger generation, indicating his worry that the cumulative injustices will lead to negative repercussions in the future.