Jamieson, Fausset & Brown

Therefore--connected with the words in Co2 5:16, "We know Christ no more after the flesh." As Christ has entered on His new heavenly life by His resurrection and ascension, so all who are "in Christ" (that is, united to Him by faith as the branch is In the vine) are new creatures (Rom 6:9-11). "New" in the Greek implies a new nature quite different from anything previously existing, not merely recent, which is expressed by a different Greek word (Gal 6:15). creature--literally, "creation," and so the creature resulting from the creation (compare Joh 3:3, Joh 3:5; Eph 2:10; Eph 4:23; Col 3:10-11). As we are "in Christ," so "God was in Christ" (Co2 5:19): hence He is Mediator between God and us. old things--selfish, carnal views (compare Co2 5:16) of ourselves, of other men, and of Christ. passed away--spontaneously, like the snow of early spring [BENGEL] before the advancing sun. behold--implying an allusion to Isa 43:19; Isa 65:17.