Whether the plagiarism label is fair here I'm not sure, and Graham captures well both the difficulty of crafting a good sermon every week and the range of pastoral opinion on how much content can be ethically borrowed. But what strikes me as unambiguously bad — and downright stupid — is the failure to give credit to the source.
Unsourced content use is hardly a problem unique to Baptist pastors. Politicians plagiarize plenty. Prominent political plagiarists include President Biden, former President Barack Obama, former first lady Melania Trump, the late Sen. John McCain (R-Ariz.), Sen. Rand Paul (R-Ky.), and many more. I should hasten to add that we often can't know if politicians who plagiarize do so wittingly. Sometimes the real plagiarist is the staffer(s) who wrote the speech — an often stranger situation, as the staffer is likely to be younger and more internet savvy than her boss and therefore (theoretically) more aware of how search engines and online opposition research work.
That public — and particularly political — plagiarism still happens in the internet era might be the definitive answer to "stupid or evil?" It is stupid, and bizarrely so, for anyone who has used the internet to imagine he can plagiarize and not get caught. Google exists. How does any would-be plagiarist not understand this in the Year of Our Lord 2021? Discovery is an inevitability.