The exhortation to walk in love and obedience merely reiterates one of the major emphases of 1 John and possibly suggests that the author is seeking to guard against antinomianism in behavior and lovelessness in attitude, both characteristic of the false teachers referred to in 1 John.
Many deceivers suggests that there is a danger this congregation may be contaminated by the false teaching. The theological dimension of it is Christological, denying that the Incarnation is real (see notes on 1 John). The teaching of Christ is regarded as the test of truth and the deceivers have run ahead of this. One of the major tests of aberrant teaching is the claim to have gone beyond the revelation in Jesus Christ to new or better “truth.” But for John and the NT as a whole, God's final revelation has occurred in and through his Son (see Heb 1:1-3).
John's words against extending hospitality to such teachers must be read against the background of the situation. Many traveling teachers and prophets were in the early church. Usually they were welcomed into the churches to teach and/or preach. This congregation is being advised to test such a person's doctrine and not allow perversive instruction in the house. One of the early Christian documents, the Didache, gives similar instruction: “Let every apostle who comes to you be received as the Lord. . . . But not everyone who speaks in the spirit is a prophet; he is only a prophet if he has the ways of the Lord. The false and the genuine prophet will be known therefore by their ways” (Bettenson, 51).