Looking to the future, Joel sees that God's blessings will be enjoyed by his people. Foreigners (ungodly) won't be allowed to enter Jerusalem because it will be holy.
Revelation 21:27 Nothing unclean and no one who does shameful things or tells lies will ever go into it. Only those whose names are written in the Lamb's book of life will enter the city.
v18
Joel sees loads of prosperity, and peace throughout the whole of Israel
v19
The places that were enemies to Israel will be deserted because they killed innocent people like Egypt and Edom. In verse 2 it mentions how God will treat those who treated Israel like enemies
v20-21
There will always be people living in Jerusalem and Judah. so this kind of shows religion won't ever end despite what people think, and people can enjoy God's presence forever.
So, loving God and doing good doesn't lead to wealth and glory. Some people seem fine without God and still have wealth and glory. But God's judgement is clear, everything outside Jesus is worthless.