Q: Why are there such dramatically variant translations of Revelation 22:14 (c.f., NASB & KJV), and does this verse suggest added conditions for eternal life?

A: (1) Why such dramatically variant translation?
The NASB reads, “Blessed are those who wash their robes,” while the KJV reads, “Blessed are they that do his commandments.” The difference in translation is due to the NASB translating from Codex Sinaiticus and other member manuscripts of the critical text, while the King James translates in agreement with Stephanus’ Textus Receptus. Without going into detail on the critical text vs. Majority Text/Textus Receptus controversy, let me just say that I generally prefer the critical text, so in this case, I believe the washing of robes to be the more accurate reading. However, the possibility that either reading could be correct necessitates handling both in respect to the second question.

(2) Does this verse represent a condition for eternal life?

(a) if read as “wash their robes” – Rev. 7:14 refers in the aorist to those who have washed their robes and come out of the great tribulation, a probable reference to those who come to Christ and perish (most likely by martyrdom) during the first half of the tribulation (thus they are kept from [ek] the great tribulation (the second half, as Jesus’ termed it, see Mt. 24:21). These who have washed their robes have made them white in the blood of the lamb. The use of the aorist indicates a one-time event, rather than an ongoing activity (ongoing activity could be indicative of works, while a one-time washing would be an obvious reference to the salvation event). If then Rev. 22:14 should be read according to the critical text, the verb washing is a present active participle (those who are presently washing), and this washing does seem to be a condition (at least) of living in the New Jerusalem. The alternative (stated in v. 15) is to be outside in a place of condemnation. While v. 14 does not explicitly reference eternal life, it seems plausible to conclude that such is the aim, especially in light of the alternative in v. 15. While some very reliable commentators suggest this is actually referencing reward for the works of believers (cf. 7:14, 19:8, and 22:14), it seems that the washing of robes should be considered in light of 7:14 (as salvation) rather than in light of 19:8 (which does not reference the robes directly, and focuses on righteous acts). Though the Revelation is for the churches (22:16), unbelievers are addressed (22:11), and thus this passage seems best to serve as a call to participate in the salvation event, which John elsewhere references as being conditioned only upon belief in Jesus (eg., Jn. 3:16).

(b)If read as “do his commandments” – This would mark the only instance in Revelation in which doing his commandments (poiountas tas entolas) would appear. While not a foreign concept to John, the idea of a hapax legomena (single instance) here is evidence against this reading. Nonetheless, in 1 Jn. 3:23, the first of His commandments is to believe in the name of Jesus Christ – and thus, the salvation event. In this context, the TR reading also would be consistent with the idea that while Rev. 22:14 is a condition for eternal life, and that in Johannine theology that condition is singularly belief in Him. The use of the plural (commandments) anticipates the further commandment of showing love (1 Jn. 3:23). Both are commandments of Christ, yet John is consistent in his presentation that only one of these brings about new life, while the other is the expected function of that new life.

The punchline is basically this: Johannine theology consistently presents only one condition for salvation – belief in Him, while he also presents – in no uncertain terms that believers are expected to walk in newness of life, and that there is additional blessing for fruitfulness.

Hope that helps…