The Christian faith is the only faith that can back up it's claims even remotely to the standards of skeptics. This is the reason that it is attacked so much more than any other faith. 'Religious exclusivity' makes total sense since there can be only one absolute truth, one absolute deity if the premise of a intelligent design is correct.
Jesus came to earth displaying the attributes of God and the final confirmation happened upon His resurrection. Therefore, one who claims to be a 'Christian', yet absolves all others in the name of one Godly attribute (saying that all roads lead to heaven), love, ignores the very words of God and thus preaches a false gospel. He endangers his own immortal soul.
NIV Ephesians 4:1-7
1 As a prisoner for the Lord, then, I urge you to live a life worthy of the calling you have received.
2 Be completely humble and gentle; be patient, bearing with one another in love.
3 Make every effort to keep the unity of the Spirit through the bond of peace.
4 There is one body and one Spirit-- just as you were called to one hope when you were called--
5 one Lord, one faith, one baptism;
6 one God and Father of all, who is over all and through all and in all.
7 But to each one of us grace has been given as Christ apportioned it.
NIV Romans 10:1-13
1 Brothers, my heart's desire and prayer to God for the Israelites is that they may be saved.
2 For I can testify about them that they are zealous for God, but their zeal is not based on knowledge.
3 Since they did not know the righteousness that comes from God and sought to establish their own, they did not submit to God's righteousness.
4 Christ is the end of the law so that there may be righteousness for everyone who believes.
5 Moses describes in this way the righteousness that is by the law: "The man who does these things will live by them."
6 But the righteousness that is by faith says: "Do not say in your heart, `Who will ascend into heaven?' " (that is, to bring Christ down)
7 "or `Who will descend into the deep?' " (that is, to bring Christ up from the dead).
8 But what does it say? "The word is near you; it is in your mouth and in your heart," that is, the word of faith we are proclaiming:
9 That if you confess with your mouth, "Jesus is Lord," and believe in your heart that God raised him from the dead, you will be saved.
10 For it is with your heart that you believe and are justified, and it is with your mouth that you confess and are saved.
11 As the Scripture says, "Anyone who trusts in him will never be put to shame."
12 For there is no difference between Jew and Gentile--the same Lord is Lord of all and richly blesses all who call on him,
13 for, "Everyone who calls on the name of the Lord will be saved."
NIV Luke 16:19-31
19 "There was a rich man who was dressed in purple and fine linen and lived in luxury every day.
20 At his gate was laid a beggar named Lazarus, covered with sores
21 and longing to eat what fell from the rich man's table. Even the dogs came and licked his sores.
22 "The time came when the beggar died and the angels carried him to Abraham's side. The rich man also died and was buried.
23 In hell, where he was in torment, he looked up and saw Abraham far away, with Lazarus by his side.
24 So he called to him, `Father Abraham, have pity on me and send Lazarus to dip the tip of his finger in water and cool my tongue, because I am in agony in this fire.'
25 "But Abraham replied, `Son, remember that in your lifetime you received your good things, while Lazarus received bad things, but now he is comforted here and you are in agony.
26 And besides all this, between us and you a great chasm has been fixed, so that those who want to go from here to you cannot, nor can anyone cross over from there to us.'
27 "He answered, `Then I beg you, father, send Lazarus to my father's house,
28 for I have five brothers. Let him warn them, so that they will not also come to this place of torment.'
29 "Abraham replied, `They have Moses and the Prophets; let them listen to them.'
30 "`No, father Abraham,' he said, `but if someone from the dead goes to them, they will repent.'
31 "He said to him, `If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.'"
Rev. 20. 11-15
11 And I saw a great white throne, and him that sat upon it, from whose face the earth and the heaven fled away; and there was found no place for them.
12 And I saw the dead, the great and the small, standing before the throne; and books were opened: and another book was opened, which is the book of life: and the dead were judged out of the things which were written in the books, according to their works.
13 And the sea gave up the dead that were in it; and death and Hades gave up the dead that were in them: and they were judged every man according to their works.
14 And death and Hades were cast into the lake of fire. This is the second death, even the lake of fire.
15 And if any was not found written in the book of life, he was cast into the lake of fire.
NIV Matthew 13:37-42
37 He answered, "The one who sowed the good seed is the Son of Man.
38 The field is the world, and the good seed stands for the sons of the kingdom. The weeds are the sons of the evil one,
39 and the enemy who sows them is the devil. The harvest is the end of the age, and the harvesters are angels.
40 "As the weeds are pulled up and burned in the fire, so it will be at the end of the age.
41 The Son of Man will send out his angels, and they will weed out of his kingdom everything that causes sin and all who do evil.
42 They will throw them into the fiery furnace, where there will be weeping and gnashing of teeth.
NIV Matthew 25:40-46
40 "The King will reply, `I tell you the truth, whatever you did for one of the least of these brothers of mine, you did for me.'
41 "Then he will say to those on his left, `Depart from me, you who are cursed, into the eternal fire prepared for the devil and his angels.
42 For I was hungry and you gave me nothing to eat, I was thirsty and you gave me nothing to drink,
43 I was a stranger and you did not invite me in, I needed clothes and you did not clothe me, I was sick and in prison and you did not look after me.'
44 "They also will answer, `Lord, when did we see you hungry or thirsty or a stranger or needing clothes or sick or in prison, and did not help you?'
45 "He will reply, `I tell you the truth, whatever you did not do for one of the least of these, you did not do for me.'
46 "Then they will go away to eternal punishment, but the righteous to eternal life."
NIV Jude 1:6-7
6 And the angels who did not keep their positions of authority but abandoned their own home--these he has kept in darkness, bound with everlasting chains for judgment on the great Day.
7 In a similar way, Sodom and Gomorrah and the surrounding towns gave themselves up to sexual immorality and perversion. They serve as an example of those who suffer the punishment of eternal fire.
The requirements of salvation are clear, the results of not worshipping the One Almighty God are equally clear.
"Unless you believe that I Am, you are lost in your sins", as John 8:23 says. This statement is one of seven where Christ declares Himself to be YHWH and is of immense theological significance. Jesus clearly claims to be the Lord God Almighty. Upon that premise, He is either a liar, a loon or He is the Lord.
There is no in between for a true Christian, there is no room for compromise on this and the correct, logical view of a Christian is that all other religious claims are inherently false and from the devil.
This statement also emphasizes that acknowlegement of Jesus as Lord God Almighty, the equal person of the Father, is an absolute requirement for salvation. We now see just what evil the Watchtower has been a part of. Their leaders are pronounced guilty of the bloodguilt of millions of souls.
Can they be forgiven? Yes, no sin other than the ultimate unbelief in Christ is unforgiveable...while they yet live in this world. Once they pass 'beyond the veil', they await the judgement of Revelation 20.