Baptism vows up to 1985 were as follows:
"Have you repented of your sins and turned around, recognising yourself before Jehovah God as a condemned sinner who needs salvation, and have you acknowledged to him that this salvation proceeds from him, the Father, through his son Jesus Christ?"
"On the basis of this faith in God and his provision for salvation, have you dedicated yourself unreservedly to do his will henceforth as he reveals it to you through Jesus Christ and through the Bible under the enlightening Holy Spirit?"
These questions, or vows, were changed in 1985 to the following:
"On the basis of the sacrifice of Jesus Christ, have you repented of your sins and dedicated yourself to Jehovah to do his will?"
"Do you understand that your dedication and baptism identify you as one of Jehovah's Witnesses, in association with God's spirit-directed Organisation*? Having answered yes to these questions, candidates are in the right heart condition to undergo Christian baptism."
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As late as 1955, a person did not need to be baptised by the Watchtower Society to be considered a Jehovah's Witness. Baptism by another Christian denomination was considered valid, provided it was as an adult by full immersion. The Watchtower 1955 Jul 1 p.412 paragraph 20 explained that re-baptism was necessary only if the previous baptism was not in symbol of a dedication, or if it was not by immersion.
It was not until 1956 that baptism by the Watchtower Society became mandatory.
* please note that nowhere in the Bible will you ever find the phrase, "God's SPIRIT DIRECTED ORGANIZATION". So, JWs are being baptized into a fictitious entity...which is appropriate for a pseudo-Christian cult.