Of course it is. But it has to be a 2-way thing. JWs love it when people of other faiths worship with them. However, they don't reciprocate. Many won't even go to family weddings that are held in churches.
Like Jesus, Jehovah's Witnesses "are no part of the world." (John 17:14) How could they ally themselves through interfaith movements with religious organizations that promote unchristian conduct and beliefs? Watchtower 7/1/93 Page 16Surely, then, we should do nothing to support interfaith movements or perpetuate false religion. Watchtower 7/15/89 Page 25
Would not offering prayers at an interfaith meeting on a Buddhist holy mountain amount to a Christian's 'becoming unevenly yoked'?
Watchtower 3/15/88 Page 9
mostly Catholics, that have noticed religion's drifting toward politics and its acceptance and approval of un-Biblical practices like interfaith, immorality, and violence. Watchtower 1/1/87 Page 29
Questions From Readers
• Why have Jehovah's Witnesses disfellowshipped (excommunicated) for apostasy some who still profess belief in God, the Bible, and Jesus Christ?
Those who voice such an objection point out that many religious organizations claiming to be Christian allow dissident views...
However, such examples provide no grounds for our doing the same. Why not? Many of such denominations allow widely divergent views among the clergy and the laity because they feel they cannot be certain as to just what is Bible truth...
Moreover, to the extent that religionists believe in interfaith, they are obligated not to take divergent beliefs too seriously...
Obviously, a basis for approved fellowship with Jehovah's Witnesses cannot rest merely on a belief in God, in the Bible, in Jesus Christ, and so forth. The Roman Catholic pope, as well as the Anglican Archbishop of Canterbury, professes such beliefs, yet their church memberships are exclusive of each other. Likewise, simply professing to have such beliefs would not authorize one to be known as one of Jehovah's Witnesses.
Approved association with Jehovah's Witnesses requires accepting the entire range of the true teachings of the Bible, including those Scriptural beliefs that are unique to Jehovah's Witnesses. What do such beliefs include?
That the great issue before humankind is the rightfulness of Jehovah's sovereignty, which is why he has allowed wickedness so long. (Ezekiel 25:17) That Jesus Christ had a prehuman existence and is subordinate to his heavenly Father. (John 14:28) That there is a "faithful and discreet slave" upon earth today 'entrusted with all of Jesus' earthly interests,' which slave is associated with the Governing Body of Jehovah's Witnesses. (Matthew 24:45-47) That 1914 marked the end of the Gentile Times and the establishment of the Kingdom of God in the heavens, as well as the time for Christ's foretold presence. (Luke 21:7-24; Revelation 11:15-12:10) That only 144,000 Christians will receive the heavenly reward. (Revelation 14:1, 3) That Armageddon, referring to the battle of the great day of God the Almighty, is near. (Revelation 16:14, 16; 19:11-21) That it will be followed by Christ's Millennial Reign, which will restore an earth-wide paradise. That the first to enjoy it will be the present "great crowd" of Jesus' "other sheep."...
...the apostle John termed as antichrists those who did not believe that Jesus had come in the flesh. They may well have believed in God, in the Hebrew Scriptures, in Jesus as God's Son, and so on.
Following such Scriptural patterns, if a Christian (who claims belief in God, the Bible, and Jesus) unrepentantly promotes false teachings, it may be necessary for him to be expelled from the congregation. (See Titus 3:10, 11.) Watchtower 4/1/86 Page 30-31 (selected quotes)
Not much chance of interfaith with words like that. Attend another church and worship and a JW could be disfellowshipped for being an anti-Christ.
Interfaith has done a huge amount of good. Christians of various denominations along with Jews (and Muslins now) come together in inter-denominational meetings frequently not far from where I live. Does everyone argue or change their beliefs? No. Do people come to a better understanding an appreciation of other faiths? Yes.
Will we see JWs at these meetings soon? I guess not.