‘The Lord is my rock, my fortress and my deliverer’ (Psalm 18:2)
Castles & forts are there to keep danger out and protect the people inside.
When God is your fortress He keeps you save from the dangers around you.
That does not mean no hardship just that it can not win.
A fortress can be laid siege to and those inside suffer from it, but if well defended with courage and hope it will hold out till the attackers run out of steam.
So when troubles come a calling defend your God fortress and trust in the strength of His defense.