It is often claimed that there are Bible verses which support the idea of guilt by association. It is true that the whole of the one body is in fact affected by the guilt of individual members; but we cannot escape out of the body (unless we leave the Lord Jesus Christ), and therefore the state of the body as a whole inevitably affects us all. However, please note that none of the passages quoted are suggesting that the sin of anyone else can enter us as if it were some bread or wine-borne disease, or that the faithful ought to have left the one body. Guilt by association, if we must use that phrase, is something we can do nothing about. We are in a sense in fellowship with the world in that we are human- we are " joined (LXX koinonio -fellowshipped) to all the living" (Ecc. 9:4); we are guilty in some way for the rejection of God's Son- we turned away from Him, and esteemed Him rejected of God (Is. 53:3,4). But we can do nothing about being members of the human race. We cannot exit from humanity, as we cannot exit from the body of Christ. Israel were told to destroy any of their number who worshipped idols; but if they failed to do this, God said that He Himself would remove that man from the community. He doesn't say that the whole nation of Israel would become personally guilty by association and therefore the whole nation would be treated by Him as the one man who was idolatrous (Lev. 20:5).
In the same way as Daniel, Isaiah, Ezra etc. were reckoned as guilty but were not personally responsible for the sins of others, so the Lord Jesus was reckoned as a sinner on the cross; He was made sin for us, who knew no sin personally (2 Cor. 5:21). He carried our sins by His association with us, prefigured by the way in which Israel's sins were transferred to the animal; but He personally was not a sinner because of His association with us. The degree of our guilt by association is hard to measure, but in some sense we sinned " in Adam" (Rom. 5:12 AVmg.) In the context of Rom. 5, Paul is pointing an antithesis between imputed sin by association with Adam, and imputed righteousness by association with Christ. In response to the atonement we have experienced, should we not like our Lord be reaching out to touch the lepers, associating ourselves with the weak in order to bring them to salvation- rather than running away from them for fear of 'guilt by association'?
Guilt by association is deeply ingrained in the human psyche- it's one of the most obstinate parts of our nature with which we have to do battle. We tend to assume that people are like those with whom they associate. The association of God's Son with us just shows how totally untrue that assumption is- and He went out of His way to turn it on its head by associating with whores and gamblers. You can see an example of the guilt by association mentality in the incident of the healed blind man in John 9. The Jews accused Jesus of being illegitimate- they mocked the former blind man about his healer: "as for this fellow, we know not from whence he is" (Jn. 9:29). When the healed man stands up for Jesus, the Jews get really mad with him: "You were completely born in sin!"- i.e. 'you're illegitimate' (Jn. 9:34). But the record reveals that the Jews knew the man's parents and had just spoken with them (Jn. 9:20). Clearly the mentality of these learned men was: 'You follow a bastard; so, you are a bastard'. Simple as that.
John Thomas faced the fellowship problem in the 19th century. The argument was put forward that whoever fellowshipped a weak brother shared his sinfulness. He clearly rejected this concept of guilt by association:
" [The] argument is that in fellowshipping [e.g.] slave-owners, and those who fellowship them, the parties so fellowshipping them are partakers with them of their evil deeds; and therefore as much slave owners and slave holders as if they actually held and drove them. The argument is not sound ..... the salvation of individuals is not predicated on the purity of their neighbour's faith, though these may be members of the same ecclesiastical organization" (John Thomas, The Herald, 1851, pp. 204, 120).