This word occurs only in Hebrews 6:20, where it is used of our Lord, who has entered within the veil as the Forerunner of redeemed mankind. It is a military term (πρόδρομος) used of the troops which were sent in advance of an army as scouts (Herod. i. 60, iv. 121, 122; Thuc. ii. 22, etc.). Again, a forerunner was sent in advance of a king to prepare the way for him (Isaiah 40:3). In the NT the Baptist becomes the forerunner of the Christ (Matthew 11:10). The author of the Epistle shows that the promise made to Abraham still awaits its complete fulfilment-a promise which is made doubly sure, being confirmed by an oath. This promise has been fulfilled by Christ, so that hope may new enter where Jesus, the Son of Man, has already entered to make atonement for us.
The use of this term πρόδρομος emphasizes the fact that Jesus has entered heaven, not as the Jewish high priest entered the Holy of Holies, to return again, but to open a way by which His people may follow, and to prepare a place for them (John 14:2).
Morley Stevenson.