John the Baptist repeated stated purpose: PREPARE the way of the Lord (Isa 40:1-11, Ps 85:9-14, Mal 3:1, Matt 11:10, Mk 1:2)
Mosaic law required PREPATATION/purifying/washing/instructions on many occasions: Ex 39:4, 30:19-21, 40:12; Lev 6:27, Lev 13:54, 13:58, 14:8-9, 15:16, 16:4, 16:24, 22:6...