Incapable of being shaken

unshakable faith.

marked by firm determination or resolution; not shakable; "firm convictions"; "a firm mouth"; "steadfast resolve"; "a man of unbendable perseverence"; "unwavering loyalty"[syn: firm ]

without flaws or loopholes; "an ironclad contract"; "a watertight alibi"; "a bulletproof argument"[syn: unassailable ]

adjective

firm , secure , solid , stable , strong , sturdy , substantial , sure , abiding , adamant , fixed , impregnable , inflexible , steady , unflappable , unsinkable , unwavering