Jesus promised believers literal mansions in heaven

"In my Father's house are many mansions: if it were not so, I would have told you" (John 14:2, KJV). The underlying Greek word, monai, is rare, appearing only here and in John 14:23, where the same root describes God making his "home" or "abode" with a believer. Its sense is close to "a place to remain," from the verb menō, to stay or abide, with no connotation of size or luxury at all.

The KJV's "mansions" actually comes from William Tyndale's earlier 1526 translation, where "mansion" still just meant an ordinary dwelling, decades before the word narrowed toward the large, opulent houses it names today. Nearly every modern translation renders this "rooms" or "dwelling places" specifically to undo the accidental upgrade English gave the word over four centuries.