Point #4, If they can't see the Trinity in the Scripture, are they really born-again believers.
There are no scripture citing that kind of judgment in regards to the dotrine of the Trinity, however, denying the deity of Christ does come with a cost of dying in their sins, but again, that does not mean they are not saved. It just means that unless they repent, they will find themselves denied at the pre tribulational rapture event for not being found abiding in Him, but know that even those that believe in His name, are saved and thus Christ is still in them which is why He will finish His work even in those left behind to face the coming great tribulation.
2 Timothy 2:
11 It is a faithful saying: For if we be dead with him, we shall also live with him:
12 If we suffer, we shall also reign with him: if we deny him, he also will deny us:
13 If we believe not, yet he abideth faithful: he cannot deny himself.
Consider this truth below:
2 Timothy 2:
18 Who concerning the truth have erred, saying that the resurrection is past already; and
overthrow the faith of some. 19 Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, let every one that nameth the name of Christ depart from iniquity. 20 But in a great house there are not only vessels of gold and of silver, but also of wood and of earth; and some to honour, and some to dishonour. 21 If a man therefore purge himself from these, he shall be a vessel unto honour, sanctified, and meet for the master's use, and prepared unto every good work.
That is why those that are His disciples are to teach other believers to be His disciples too, and not just write them off when they go astray and stop believing in Jesus Christ.
1 Corinthians 6:
19 What? know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?
20 For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's.
John 1:
12 But as many as received him, to them gave he power to become the sons of God,
even to them that believe on his name: 13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
Colossians 1:
27 To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory:
28 Whom we preach, warning every man, and teaching every man in all wisdom; that we may present every man perfect in Christ Jesus:
So what a believer builds on that foundation which was laid in Christ Jesus will be judged, but he is still saved.
Remember those coming out of the great tribulation had to have their robes washed clean by the blood of the Lamb, thus indicative of those who had believed in Him, even in His name, but had died in their sins. That can be applicable towards those that deny His deity to even those that sown to the flesh in reaping corruption.
Revelation 7:
13 And one of the elders answered, saying unto me, What are these which are arrayed in white robes? and whence came they?
14 And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.
15 Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.
16 They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat.
17 For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of waters: and God shall wipe away all tears from their eyes.
So there will be weeping and gnashing of teeth that these saints will need a miracle from God to get over their loss as the prodigal son will find that he is still son even though he gave up his first inheritance for wild living.
They will be destroyed from being that vessel unto honour in His House to become that vessel unto dishonour in His House as even then, they will testify to the saving power of God in Jesus Christ for all those that believe, even in His name.
But the door to the Marriage Supper is still open and thus the call to look to the author and finisher of our faith to help us lay aside every weight and sin to depart from iniquity and be found abiding in Him when the Bridegroom comes for the ready bride.
Point #5, Leading up to Pentecost, the Baptism in the Holy Spirit was spoken of as something prophetic: take note of the future tense in Mt. 3:11; Mk. 1:8; Luke 3:16; Jn. 1:33; Acts 1:5. Then came Pentecost which was the Holy Spirit first filling the room and then filling the disciples, hence an immersion into the Spirit. From that point on, the baptism of the Holy Spirit was described as an historical event. Note the aorist tense used in Acts 11:16 and I Cor. 12:13.
Actually, it was not the Holy Spirit filling the room, but a sound from heaven as of a rushing mighty wind filled all the house where they were sitting.
Acts 2:1And when the day of Pentecost was fully come, they were all with one accord in one place.
2 And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. 3 And there appeared unto them cloven tongues like as of fire, and it sat upon each of them.
4 And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance
The Holy Spirit has been given the parameter of being known by dwelling within us and not outside of us where the spirits of the antichrist dwell so it is important to stick to what the scripture says as a sound from heaven filled the room.
John 14:
16 And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
17 Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
1 John 4:1Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world....
4 Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world.
Some have taken this verse out of context to justify identifying the presence in the place as being the Holy Spirit, but they err not knowing the scripture.
Matthew 18:
19 Again I say unto you, That if two of you shall agree on earth as touching any thing that they shall ask, it shall be done for them of my Father which is in heaven.
20 For where two or three are gathered together in my name, there am I in the midst of them.
This reference was about prayer and Jesus giving His promise of being our Mediator between us and God. "In the midts of them" is not referring to being among them in Spirit, because whenever Jesus refers to the Spirit, Jesus uses the pronoun "he" or "him" instead of "I" which when using "I" in verse 20 above, Jesus was talking about Himself in what He will do in the future in regards to prayer in verse 19.
Anyway, clarity is needed as keeping the faith is the good fight.
2 Corinthians 13:
5 Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?