One of the best arguments for evangelism as the task of every Christian comes from the image of the Christian’s armor in Ephesians 6. The NRSV states it very nicely: “As shoes for your feet put on whatever will make you ready to proclaim the gospel of peace,” v. 15.
Every Christian needs every piece of the armor. Paul says it twice, for emphasis:
Put on the whole armor of God, so that you may be able to stand against the wiles of the devil, v. 11.
Therefore take up the whole armor of God, so that you may be able to withstand on that evil day, and having done everything, to stand firm, v. 13.
Part of that essential armor are ready shoes, a desire to move out with the gospel. Vincent M. Smiles agrees with that as he sees the sword of the Spirit as an offensive weapon: “evangelization, that is, sharing the gospel, is part of the believer’s task” (“Ephesians,” in New Collegeville Bible Commentary: NT, p. 618).
The preparation or readiness to proclaim the gospel of peace is not begrudging, but contains an enthusiasm or zeal that makes one want to always put feet forward for the glad news of salvation. Among T. S. Green’s glosses for the Greek term hetoimasia (only here in NT) is “alacrity.” Eagerness. Several Brazilian translations use “zeal.” Another renders it as “enthusiasm.”
If such an eagerness to share the gospel is not characteristic of a Christian, he is missing a vital piece of his armor and will fall quickly and suddenly to the enemy.