Satan will stop at nothing to take down as many as he can and that means he needs to get people to beleive somthing other then a God that saves and sets them free.
If he can get people even christians to take our eyes off God and focus on somthing else then he has us right were he wants us.
The dart of death or the sting of the wicked is sin. By taking the shield of faith we can overcome sin. Because though faith sin is forgiven:
To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me. Acts 26:18
Through the sanctification of faith, sin is forgiven, the darts will be quenched.