The life of democracy lies in individual freedom.

Literal

Democracy's life [topic-は] individual's freedom [at-に] exists.

An abstract にある construction: 'X is in Y' meaning 'X lies in / consists in Y.' The spatial ある ('to exist') is extended metaphorically here — 'lies in,' 'is found in,' 'consists of.' This is a slightly formal, aphoristic register typical of essays.