Many will outright reject Jesus, and they have that choice. Many will reject Jesus after going through some time of difficulty.
In Romans 1:18-32 we can read passages related to God’s wrath and man’s depravity. Here, Paul clearly lays out the inevitable downward spiral into sin. First people reject God; next they make up their own ideas of what a god should be and do; then they fall into sin-sexual sin, greed, hatred, envy, murder, fighting, lying, bitterness, gossip. Finally they grow to hate God and encourage others to do so.
God does not cause this steady progression toward evil. Rather, when people reject Him, He allows them to live as they choose. Once caught in the downward spiral, no one can get out of it by oneself. When we are in sin/sinning, we can only trust Christ to place us on a path of escape.
A time of difficulty is always going to be a time of teaching if God has our best interest at heart. Rejecting our only help during a difficult time is foolish-you don’t want to miss His teaching.
Portions of commentary from The One Year NIV Devotional NT, January 4.