Why can't God give people a second chance after they reject Christ?
Because God has already given the highest and only sufficient provision for salvation—His own Son, who lived, died, and rose again. When that sacrifice is rejected, no greater remedy remains; God's hands are tied, and Scripture says it is appointed once to die, then judgment.
Les teaches that God gave the best that all of heaven and the Godhead contained, sent His Son to earth, put Him through 33 years among sinful men, and He went to the cross, suffered, died, and arose. To respond, "that's not enough," spurns the work of the cross. Les explains that those who cannot understand how much God gave up on our behalf may question Him, but when His provision is spurned, He has every right to consign people to a lost eternity. Les says he hates to see people lost and cannot make excuses for them, because God suffered to such an extent for everyone's salvation that when they spurn it, there is nothing else God can do. His hands are tied; He cannot come back and say He will give a second chance. That is why it is appointed once to die, and after that the judgment.