Jesus promises to ask the Father to send us the Holy Spirit (Jn 14:16), but many people will not accept, see, or recognize the Spirit (Jn 14:17). Jesus calls "the world" these people who cannot accept the Spirit.
The world are those who do not obey God's commandments (Jn 14:21-22). Those in the world are set upon "carnal allurements, enticements for the eye, the life of empty show" (1 Jn 2:16). The worldly are usually "lovers of pleasure rather than of God" (2 Tm 3:4). "They pervert the gracious gift of our God to sexual excess and deny Jesus Christ, our only Master and Lord" (Jude 4). "These sensualists, devoid of the Spirit, are causing divisions among you" (Jude 19). Worldly people "go about in a way which shows them to be enemies of the cross of Christ" (Phil 3:18).
Technically, those in the world would not be in God's Church, for Jesus has chosen His followers out of the world (Jn 15:19). Nevertheless, many who are "enamored of the present world" (2 Tm 3:10) are church-goers. They may even be very active leaders in the church, but "make a pretense of religion" and "negate its power" (2 Tm 3:5).
Those in the world will seem stronger than those committed to Christ. However, the world cannot receive the Spirit, Who is Power from on high (see Lk 24:49; Acts 1:8). Therefore, those in the Spirit are stronger than those in the world (see 1 Jn 4:4), and by Jesus' grace they overcome the world (Jn 16:33).