Withal taking up the shield of faith. The θυξεός was a large oblong shield covering a great part of the body, not the ἀσπίς, smaller and more round. Faith, in its widest sense, constitutes this shield—faith in God as our Father, in Christ as our Redeemer, in the Spirit as our Sanctifier and Strengthener—faith in all the promises, and especially such promises as we find in Revelations 2.
and 3. "to him that overcometh" (comp. promise to Ephesus, Revelation 2:7) Wherewith ye shall be able to quench all the fiery darts of the evil one. "Fiery darts" were weapons tipped with inflammable materials, firebrands, curiously constructed, adapted to set on fire.
Metaphorically, considerations darted into the mind inflaming lust, pride, revenge, or ether evil feelings, emanations from the great tempter, the evil one. That such considerations sometimes start up suddenly in the mind, against the deliberate desire, sometimes even in the middle of holy exercises, is the painful experience of every Christian, and must make him thankful for the shield on which they are quenched.
An act of faith on Christ, placing the soul consciously in his presence, recalling his atoning love and grace, and the promises of the Spirit, will extinguish these fiery temptations.