BFD
Most new transations have deleted that rendering. NIV for example reads: 7 - "For ther are three that testify: 8 - the Spirit, the water and the blood, and the three are in agreement." The reason for the deletion is the words "the Father, the Word and the Holy Spirit" are not found in any manuscript earlier that the late manuscripts of the Vulgate. So, most scholars and translators feel that they were not part of the original.
Many trinitarians have criticized the NWT for its biased unitaraian views. But it should be noted that they are not above slanting their translations to their views. For example, compare John 1:18. NIV reads "No one has ever seen God, but God the One and Only who is at the Father's side, has made him known." It is only the footnote that clarifies this confusing rendering. "14,18 Or the Only Begotten"