Charles Ellicott Commentary Matthew 3:10

"And even now the axe lieth at the root of the trees: every tree therefore that bringeth not forth good fruit is hewn down, and cast into the fire." — Matthew 3:10 (ASV)

Now—Rather, already. This indicates the present reality of an act that is no longer in the future.

The ax is laid unto the root of the trees—The symbolism that viewed “trees” as representatives of human characters, nations, and institutions had already been recognized in Isaiah’s parable of the vine (Isaiah 5:1–7) and in Jeremiah’s parables of the vine and the olive (Jeremiah 2:21; Jeremiah 11:16). The Baptist’s application of this symbol was simply a natural extension.

Judgments that were only partial or corrective were like the pruning of branches (John 15:2). Now, however, the ax was laid to the root, and the only alternative was preservation or destruction. For the unfruitful tree, the doom was fire.