Another major problem in the gospel that the JWs is preaching is the concept of organizational baptism and organizational salvation.
Nowhere in all of the teachings of Jesus or his apostles is there any indication that a convert had to verbally acknowledge being baptized into a congregation as a prerequisite for immersion. The baptism was carried out in the name of the Father, Son, and the Holy Spirit. There was never any concept of being baptized into or in relation to the congregation doing the baptizing. This is a concept that crept into the Church after the deaths of the apostles.
Salvation is another major problem. Nowhere in Scripture is there any indication that salvation is contingent upon congregational / organizational membership. The focus was always on relationship with Christ.
For example: take the case of the congregation in Ephesus; one of the congregations founded by Paul. Upon the death of Paul and the other Apostles, Ephesus slid into false teachings and practices. Did an individual have an obligation to stay in the congregation? Would the individual be in jeopardy of losing out on their salvation for leaving the congregation for conscientious reasons?