If one has to be saved do they need to be a Christian?
Acts 26:28-29 (New International Version)
28 Then Agrippa said to Paul, "Do you think that in such a short time you can persuade me to be a Christian?"
29 Paul replied, "Short time or long—I pray God that not only you but all who are listening to me today may become what I am, except for these chains."
Paul said yes. Having Confidence that you are God's people and flock is not a sin.
It is unfortunate that time has blurred christianity so it covers a widely massive collection of contradictory religions that are at odds with each other and do not even worship the same God anymore. But this is a predicted thing. So we have to as witnesses clarify this more than just saying "christian" which indeed we are but we have to separate ourselves for false weeds among christianity that have set up false gods and teachings.
The bible shows that false teachers, savage wolves will come among God's people with false Gospels/teachings and we must recognise this.
Acts 20:29-31 (New International Version)
29 I know that after I leave, savage wolves will come in among you and will not spare the flock. 30 Even from your own number men will arise and distort the truth in order to draw away disciples after them. 31 So be on your guard!
.Galatians 1:8-9 (New International Version)
8 But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let him be eternally condemned! 9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let him be eternally condemned!
At this time I truly believe Jehovah's witnesses are God's people, I personally tested them against the rest of the Christian religions and their teachings and found Jehovah's witnesses to be the most Biblically true religion by about a mile and a half. but it is for each person to decide for themselves.
All roads do not lead to God! "Narrow" is the path leading to Jesus our way to reconciliation with Jehovah his father. Jesus isn't a figurehead sat upon a load of different teachings and waring people, but he has one truth, one message and he got it from his father. If you think you have found the people in this time that have seen through the Savage wolves/weeds and and recognisably teach the real message from the Bible then it is no sin to commit to them as God's flock and people. To hold something back and say "maybe they are" is not giving a full commitment to the flock.