Though, by his own admission, the influence from his busking days is unshakable.
From the washingtonpost.com
It's built on an unshakable foundation that not even she completely understands.
From the denverpost.com
As circumstantial evidence, he cites the early church's unshakable belief in it.
From the time.com
He is a successful entrepreneur with an unshakable belief in his own abilities.
From the businessweek.com
Add in an unshakable mental game, and she's virtually unbeatable on this surface.
From the sportsillustrated.cnn.com
Bush's unshakable faith in the power of personal diplomacy dictated conciliation.
From the time.com
Campbell-Bannerman, like other Liberals, held an unshakable belief in free trade.
From the en.wikipedia.org
He has an unshakable love of his wife and researches how to break her out of jail.
From the suntimes.com
In my lifetime I can't recall such an unshakable foundation to an Albion side.
From the expressandstar.com
More examples
Firm: marked by firm determination or resolution; not shakable; "firm convictions"; "a firm mouth"; "steadfast resolve"; "a man of unbendable perseverence"; "unwavering loyalty"
Unassailable: without flaws or loopholes; "an ironclad contract"; "a watertight alibi"; "a bulletproof argument"
(unshakably) determinedly: with determination; in a determined manner; "he clung to the past determinedly"