credobaptist

The story

1. Proto-Indo-European*ḱerd-
2. Proto-Indo-European*ḱḗr
3. Proto-Indo-European*dʰeh₁-
4. Proto-Indo-European*ḱérddʰeh₁ti
5. Proto-Indo-European*ḱréddʰeh₁ti
6. Proto-Italic*kresdō
7. Latincrēdō
8. Old Frenchcredo
9. Middle Englishcredo
10. Englishcredo
11. Proto-Indo-European*gʷeh₂bʰ-
12. Proto-Indo-European*gʷh₂bʰyéti
13. Proto-Hellenic*gʷápt͏̌ō
14. Ancient Greekβάπτω (báptō)
15. Ancient Greekβᾰπτῐ́ζω (băptĭ́zō)
16. Ancient Greekβαπτιστής (baptistḗs)
17. Latinbaptista
18. Old Frenchbaptiste
19. Middle Englishbaptiste
20. Englishbaptist
21. English todaycredobaptist

From credo + baptist.