The activity of Satan against believers is mentioned in various ways throughout the New Testament.
Satan tempts believers to lie (Acts 5:3); he accuses and slanders them (Rev. 12:10); he entices them toward sexual sin (1 Cor. 7:5); he places obstacles in their path (1 Thess. 2:18); he causes persecution (Rev. 2:10); and he causes pseudo-Christians to infiltrate among true Christians to promote confusion and division in the church (Matt. 13:38, 39).
The Christian’s defense involves being on guard, sober, vigilant (1 Pet. 5:8), taking a stand against the devil and resisting him (v. 9; James 4:7; Eph. 6:11–18).