You cannot conclude from a conversation with someone you have never met before in your life that they exhibited much more the fruits of the Spirit in their behavior. They are taught to be cordial, to behave kindly, etc.
True, a pagan can be cordial, and it takes time to really get to know anybody. On the other hand, I've known a decent number of people I knew were Christian, before the subject ever came up, by their abiding kindness, control others lack, selflessness and friendliness that was consistent, things of the Spirit that are impossible to fake, over the long haul. There is a certain way a true Christian behaves, of any decent length of time in the faith. There are the fruits of the Spirit, as well as Christian spiritual discernment.
Matthew 7
13 Enter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat:
14 Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.
15 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.
16
Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?
17 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
18 A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.
19 Every tree that bringeth not forth good fruit is hewn down, and cast into the fire.
I have JWs in my family and trust me they are not like the young men that came to your door.
When I was a nobody in the world, they would talk to me.
The moment the Lord saved me, they no longer talk to me.
Notice how the devil never comes and tells an UNbeliever that he/she is going straight to hell, but when the Lord saves a person, the devil comes immediately and tell him/her that they are going straight to hell?
I've also experienced the other side of the coin, not just JWs, but they and a few other exclusive groups that have rabid members who believe, in their heart of hearts, that nobody else is saved. This is something they will seldom reveal, though, to a non-member.
You'll find most all cults have this in their doctrine, the modus operandi of cult false prophets to have doctrinal exclusives. This is where their power is derived from, hoodwinking people into thinking they have something nobody else has, that they're special, which is also seductive of peoples' egos. Exclusive false doctrines are a means of enslaving an audience, creating that power base of control over people, who can't get what they offer anywhere else. Get them to believe the exclusives are the truth, and you have a slave. In fact, there are a number of these groups with some very nasty, evil old timers. This is one reason I have difficulty holding out a lot of hope for the dyed in the wool, old members, many who are hardened cultists, of dead, dark hearts. The other reason is simply scripture, keeping in mind God does not fail:
John 16:13 However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come.
When somebody, of any stripe, has been long in their faith and doesn't have a grip on truth, cult or whatever, this much concerns me, as it's evidence a person isn't really saved, that the Holy Spirit hasn't been operating in and on them. But I do hold out great hope for the sincere young, a long history of many emerging from all sorts of cults, who I believe were saved, despite being cult members. At the center of Christianity is repentance, a person coming to believe in and put their faith in Jesus Christ, the simple, saving gospel. Everybody even comes to Christ a sinner, much less of any doctrinal depth, salvation not a matter of being expert or even fully aware of many things of God, which can only be learned over time. One can even get this saving message from a charlatan preacher, who, himself, is on the way to hell. And to, out of the gate, state a person is not saved who claims the Lord Jesus, for being in some doctrinal error, is idiotic hypocrisy since, again, we have all been of mistaken doctrine, been steeped in ignorance, yet saved, all of us still of some mistaken doctrine, no such thing as a Bible "know it all." So, who is going to play God and determine the threshold of doctrinal error, when somebody is, at least, of profession of faith in the Lord Jesus? Who believes this even a Christian attitude, when we, ourselves, have been in error and are still, to some degree, in error of the word of God? I know I'm not certain of a body of eschatology. Also, as you mention, it's the devil in the accusation and slander business, and is that not a very poor behavioral role model for a Christian? Romans 8:33-34.
As to the accusations, yes, you're so right. The devil is all about condemnation, slander and trying to sow doubt, as soon as somebody becomes a Christian. I believe he and his demons tend to leave his own alone, on the persecution front. Actually, I'd be very concerned, as a Christian, if the devil wasn't at it. There came a time when I began to find joy in this, though, as, when his shorts are in a bunch, it's often because you're doing something right he doesn't like. It's a good thing, having something the devil really hates! (Where there's smoke, there's fire.)
Matthew 5
10 Blessed are they which are persecuted for righteousness sake: for theirs is the kingdom of heaven.
11 Blessed are ye, when men shall revile you, and persecute you, and shall say all manner of evil against you falsely, for my sake.
12 Rejoice, and be exceeding glad: for great is your reward in heaven: for so persecuted they the prophets which were before you.
