The mystery of which was hidden for ages and generations [from angels and men], but is now revealed to His holy people (the saints), Colossians 1:26 (AMP)
What was the mystery that was hidden? The redemptive work of Jesus Christ that was made available to all.
The greek verbs used in this verse, means that there was a sudden change. The Gospel was hidden, but it suddenly was made known—to us.
The presence of Jesus Christ created a sudden and dramatic change—His death, burial, and resurrection, provided a way for us to change our destination from Hell to Heaven.
Since the presence of Jesus Christ created a dramatic change in my future destination (because I've placed my faith in Him), that same presence should have a dramatic change on my life—daily!
Living in the presence of Jesus Christ as I live daily is done only if I am permeated with a deep sense of reverence for God (Acts 9:31; MSG).