Terror management theory (TMT) posits that mortality salience (MS) leads to more negative perceptions of persons who oppose one's worldview and to more positive perceptions of persons who confirm one's worldview. Recent failed replications of classic findings have thrown into question empirical validity for this established idea. We believe, that there are crucial methodological and theoretical aspects that have been neglected in these studies which limit their explanatory power; thus, the studies of this registered report aimed to address these issues and to directly test the worldview defense hypothesis. First, we conducted two preregistered lab studies applying the classic worldview defense paradigm. The stimulus material (worldview-confirming and -opposing essays) was previously validated for students at a German university. In both studies, the MS manipulation (between-subjects) was followed by a distraction phase. Then, in Study 1 (N = 131), each participant read both essays (within-subjects). In Study 2 (N = 276), the essays were manipulated between-subjects. Credibility attribution towards the author was assessed as the dependent variable. In both studies, the expected interaction effects were not significant. In a third highly powered (registered) study (N = 1356), we used a previously validated worldview-opposing essay. The five classic worldview defense items served as the main dependent measure. The MS effect was not significant. Bayesian analyses favored the null hypothesis. An internal meta-analysis revealed a very small (Hedges' g = 0.09) but nonsignificant (p = .058) effect of MS. Altogether, the presented studies reveal challenges in providing convincing evidence for this established idea.