Excellent, extreme in a good way. "Totally radical, dude!" Dated 1980s-90s surfer superlative. Still used occasionally with ironic affection.
The word's root (itself ironic — radix means root) points at something Scripture takes very seriously: addressing problems at the root, not the symptom. "Every tree therefore that does not bear good fruit is cut down and thrown into the fire" (Matt 3:10) — John the Baptist came with an axe at the root. "The love of money is a root of all kinds of evils" (1 Tim 6:10). Biblical ministry is radical in the etymological sense: going to the root of sin, the root of unbelief, the root of bitterness. The flattened surfer usage is harmless; the original meaning is biblically serious.
The dated surfer superlative obscures the theologically weighty original: from the root. Christian ministry is radical in the original sense — root-level.
Most human "solutions" to moral problems are symptomatic: manage the anxiety, medicate the depression, outlaw the offensive word. Scripture diagnoses at the root and cures at the root. Jesus: "Out of the abundance of the heart the mouth speaks" (Matt 12:34) — the speech problem is a heart problem. Paul: "Put to death therefore what is earthly in you" (Col 3:5) — not manage but kill, at the root. Christian ethics is radical in the proper sense. When you hear "radical" as a surfer's superlative, hear the older meaning underneath.
Matthew 3:10 — "Even now the axe is laid to the root of the trees. Every tree therefore that does not bear good fruit is cut down and thrown into the fire."
Hebrews 12:15 — "See to it that no "root of bitterness" springs up and causes trouble, and by it many become defiled."
1 Timothy 6:10 — "For the love of money is a root of all kinds of evils."
Colossians 3:5 — "Put to death therefore what is earthly in you."
"Radical, dude" is fun retro. The word's real meaning is root-level. Christian ministry kills sin at the root, not the leaf.
“Dude, that skate trick was totally radical.”
“Even now the axe is laid to the root of the trees.”