Norman L. Geisler passed away on Monday. A philosopher, theologian and apologist, he changed the world of Protestant Christian thinking. At least one Catholic philosopher has also expressed real appreciation for Geisler.

Fiery, often feisty, Geisler wrote more than 80 books on a prodigious range of topics including ethics, theology, Bible difficulties, comparative religion and more; but especially on Christian apologetics.

No armchair scholar, Geisler was tireless in networking and organizing to promote discipleship of the Christian mind. He founded and was the first president of the Evangelical Philosophical Society and the International Society of Christian Apologetics.

Remarkably, he founded not one but two seminaries. Southern Evangelical Seminary in Charlotte, NC, established in 1992, was the first modern seminary focused primarily on teaching and researching reasons for Christian belief. And until just months ago he was Chancellor and Distinguished Professor of Apologetics at Veritas Evangelical Seminary, which he co-founded in Santa Ana, Calif., in 2008.

He was one of just a handful of thinkers and writers who in the 1960s and 1970s injected new life into Christian philosophy and apologetics. By example and argument, he demonstrated the intellectual legitimacy of conservative Christian doctrine and ethics.

Geisler’s writing, teaching and leadership have directly influenced generations of scholars, pastors and teachers. His impact can be traced directly to The Stream.

Christianity owes him a debt of gratitude far beyond what it will ever know.