I mentioned this is passing in a Bible reading, and I'm not sure people really understood what I was talking about. So I thought I'd clarify it here.
It is a well-known fact that J. N. Darby believed someone could be born again without being sealed by the Holy Spirit. Indeed, the falling-out between Darby and F. W. Grant was over this very issue: FWG taught that a believer is sealed with the Holy Spirit at the moment of new birth.
I don't know how many times I've read his "On Sealing with the Holy Ghost" (Collected Writings of J. N. Darby, Volume 31, pp. 254–280). The first time I read it, I was struck with this statement:
That a person may be born again, and not have received the Holy Ghost, is perfectly certain according to Scripture, for "whosoever believeth that Jesus is the Christ is born of God," and this the disciples did while Christ was on earth, but could not have the Holy Ghost, which did not come until the day of Pentecost; though they had life, and were clean through the word. (p. 262)The logic here is pretty much irrefutable; but there is some question as to whether we can apply that to believers today: of course the disciples weren't sealed with the Holy Spirit before He descended! But now that the Holy Spirit has come, is it still possible to be born again without being sealed?
I think the answer to that lies in John 14:1, "ye believe on God, believe also on me".
There is no question that God justifies the one who believes Him (Romans 4:5). We've covered this ground many times before, so we needn't go into great detail now. But Romans is clear that all God is looking for is for sinners to believe Him. Abraham, scripture tells us, was counted righteous when he believed what God told him about his having a son (Genesis 15:3–6). God has set the lowest possible bar: believe Him, and He counts you righteous. In fact, Romans goes farther even than that, and assures us that when someone believes God, God counts that person as one to whom He will not account sin (Romans 4:6–9). So if we believe God, He counts us righteous; and when He counts us righteous, He also counts us as people whose sins He will not count. In other words, it's not possible for God to think of sin in connection with someone who believes Him.
I've said before that this is Old Testament truth, and it certainly is. Romans 4 makes that argument very clearly: the whole point of Romans 4 is to demonstrate that righteousness without works is the teaching of the Old Testament. God has never counted anyone righteous on any other basis than faith.
But the sealing with the Holy Spirit is explicitly not Old Testament truth. John 7:39 clearly names the coming of the Holy Spirit as a result of the exaltation of Christ. Peter takes up this theme in Acts 2, and says that the [very visible] signs of the Holy Spirit's presence in and among the disciples was proof that Christ has been glorified in heaven (Acts 2:32–33). In other words, he claims that the Holy Spirit's presence on earth was a direct result of Christ's sitting on God's right hand in Heaven.
So Romans says that a sinner is justified when he believes God (Romans 4:5). But John and Ephesians say that we are sealed with the Holy Spirit when we believe on Christ (John 7:39; Ephesians 1:12–14). Is there a difference between believing God and believing on Christ? Apparently there is, because the Lord Jesus said, "ye believe on God, believe also on me" (John 14:1).
Let's consider the story of Paul meeting John's disciples in Ephesus (Acts 19:1–7). There's no doubt they had believed God (v. 2); they were on their way to Heaven, their sins all forgiven. But they hadn't received the Holy Spirit (v. 2). So Paul told them they needed to believe on the Lord Jesus (v. 4), and he baptized them in the name of the Lord Jesus (v. 5). Then, after he laid his hands on them, they received the Holy Spirit (v. 6).
Were they justified before Paul met them? Of course they were! They had believed God (v. 2), and Romans assures us that God justifies the one who doesn't work but believes (Romans 4:5). So they certainly were justified. But they hadn't received the Holy Spirit, because they hadn't believed on Jesus Christ (Acts 19:4–5).
And this is exactly what Ephesians 1:13 affirms, isn't it? It is having believed on Christ that we are sealed with the Holy Spirit (note the "in whom" in v. 13 refers back to "the Christ" in v. 12).
Can the same thing happen today? Certainly! It is the revelation of Christ ascended to God's right hand that is followed by the sealing with the Holy Spirit. God has set that bar as low as possible for justification and new birth: all He wants is for someone to believe Him. But the bar for the sealing with the Holy Spirit is much higher: it's believing on a risen, ascended, and glorified Christ. Does that mean someone can't be born again and sealed with the Holy Spirit at the same time? Of course it doesn't! But it certainly means that in many (most?) cases, there is some finite period of time between those two events.
So what is the sealing with the Holy Spirit? Galatians 4 says it's the difference between being children and being sons (Galatians 4:1–7). Make no mistake: children of God clearly are part of the family, but they're still treated like little more than the domestic staff (v. 1). Sons, on the other hand, are heirs, on intimate terms with the Father, and fully involved in the family's business and interests (v. 7). And what is the effect of the Spirit's presence in our hearts? It is confidence in God as Father (v. 6). Romans 8:15–18 echoes this same idea, perhaps in more detail.
Johnny D. says it this way:
I add here what Scripture plainly states. If a soul can in truth before God say, Abba, Father, that soul is sealed. If a person really knows that he is in Christ, and Christ in him, he is sealed. If the love of God is shed abroad in the heart, the man is sealed. (Rom. 8; Gal. 4; Rom. 13; John 14; Rom. 10.) Other proofs may be given of if, for the whole life of a man is, save particular failures, the evidence of the Spirit of God dwelling in him; but I take the simplest and most immediate evidence in a man's soul purposely and such as are in terms stated in Scripture. Now what hinders the simple acceptance of this truth is, that the full doctrine of redemption is not believed. (p. 274)
The testimony of Scripture is that Christ has ascended to God's right hand, and I am accepted in Him there. God sees me as complete in Christ. Our place is to honour Him here, while we gaze on Him there (Colossians 3:1–4; 2 Corinthians 3:18). This is the central truth of Christianity: God isn't improving flesh, He accepts me only in Christ. It is as we accept and are content with that place that we begin to walk as Christians.
So yes, I am quite convinced that a man or woman can believe God (thus having eternal life) and not be content to rest in Christ (thus not having the seal of the Holy Spirit). I'm glad to have that off my chest, so to speak.