Science keeps shrinking the space religion used to occupy, and eventually it will explain everything, leaving no room for God.

Why people find it persuasive

The historical pattern is real: phenomena once attributed to divine action (disease, weather, the origin of species) have repeatedly turned out to have natural explanations, so extrapolating that trend to its completion feels like a reasonable induction.

Important distinctions

• • God-of-the-gaps arguments (God as a placeholder for current scientific ignorance) vs. arguments from what science itself reveals (fine-tuning, contingency, intelligibility).
• • Explaining a mechanism vs. explaining why there is a mechanism, or why it is orderly and mathematically describable at all.
• • Historical retreat of specific bad theological explanations vs. the retreat of theism as a whole philosophical position.
• • Methodological naturalism as a working assumption of science vs. metaphysical naturalism as a worldview conclusion.

Christian response

• • Distinguish sharply between a genuine 'God of the gaps' argument (inserting God to explain a specific unexplained mechanism, which is indeed a fragile and historically unreliable strategy) and arguments that draw on things science itself has revealed and confirms with increasing precision, like the universe's beginning, its fine-tuning for life, and the deep mathematical intelligibility of nature — these are not gaps being plugged but positive data points that many philosophers (theist and non-theist) treat as needing explanation regardless of future scientific progress.
• • Point out this objection assumes without argument that all remaining open questions are of the same 'gap' kind as historically-resolved ones (disease causation, weather patterns), when the deepest issues raised by theistic philosophers — why there is anything contingent at all, why the laws of nature are the way they are rather than otherwise, why the universe is comprehensible to reason — are not mechanistic gaps science is designed to fill, since science presupposes an orderly, intelligible universe rather than explaining why one exists.
• • Bring up that leading scientist-theologians and philosophers of science (like John Polkinghorne, Francis Collins, or Alvin Plantinga on methodology) argue that science, by its own working assumptions (methodological naturalism), is simply not equipped to address certain kinds of questions — such as why there is a universe governed by laws at all — so 'science will eventually explain it' quietly smuggles in an unproven assumption that these questions are actually within science's domain in the first place.
• • Note the historical record is more mixed than the 'religion in retreat' narrative suggests: several major modern sciences (the big bang model, genetics) were pioneered or significantly advanced by theists (Georges Lemaître, Gregor Mendel) who saw no tension between their science and their theism, and many leading contemporary scientists remain religious believers, which complicates any simple story of science steadily eroding all grounds for belief.
• • Acknowledge honestly that many specific historical religious claims about the natural world were indeed wrong and rightly corrected by science (a geocentric universe, a young earth in some traditions), and this correction is a healthy example of theology needing to be revised by better evidence — but conflating that with the claim that all theological content whatsoever will eventually be displaced is a much larger and unproven extrapolation.

Christian counterresponse

Theists respond that some of these questions (like why there is something rather than nothing, or why the universe is governed by any laws at all) are not empirical gaps awaiting a future mechanism but different in logical kind — they ask about the existence and character of the framework within which all scientific explanation itself operates, so no amount of within-the-universe scientific progress, however impressive, addresses that different level of question by definition.