Mark 1:2-3 Commentary: The Prophesied, Preparing Messenger From the Wilderness
Though Mark does not quote the Old Testament as much as the other gospel writers, he begins with a combination (testimonium) of three Old Testament quotations which foretell of a messenger sent by the LORD — who will prepare the way of the LORD. This person will be calling out in the wilderness in order to roll out the red carpet for God Himself — who will save and reign over His people as King.