Arthur W. Pink observes the following on the meaning of “taste”:
Second, they had “tasted” of the heavenly gift. To “taste” is to have a personal experience of, in contrast from mere report. “Tasting does not include eating, much less digesting and turning into nourishment what is so tasted; for its nature being only thereby discerned it may be refused, yea, though we like its relish and savor, on some other consideration. The persons here described, then, are those who have to a certain degree understood and relished the Revelation of mercy; like the stony-ground hearers they have received the Word with a transcient joy” (John Owen). The “tasting” is in contrast from the “eating” of John 6:50-56.[6]
Dr. Grudem observes the following in a footnote about the word “taste”:
The word tasted is also used in Heb. 2:9 to say that Jesus “tasted death,” indicating that he came to know it by experience (but “tasted” is an apt word because he did not remain dead). The same could be true of those who had some experience of heavenly gifts, as can be true even of unbelievers (cf. Matt. 7:22; 1 Cor. 7:14; 2 Peter 2:20–22). In Heb. 6:4–5 these people’s experience of the Holy Spirit’s power and of the Word of God was of course a genuine experience (just as Jesus genuinely died), but that by itself does not show that the people had an experience of regeneration.[7]
What is the heavenly gift? Commentators and preachers are divided on this one although the majority think that it either refers to the Lord Christ (e.g. Gill, Com. Cri. & Expl., Steve J. Cole, ) or the Holy Spirit (e.g. Owen, Pink, Henry, Grudem, Piper). Both have good reasons to think so although as Pink observes, there is not a great difference since ‘the difference is without a distinction, for the Spirit is here to glorify Christ, as He came from the Father by Christ as His ascension “Gift” to His people.’[6]
John 4:10 seems to be a strong verse to see “the gift of God” which came down from heaven to be the Lord Jesus Himself. Note that the passage does not speak of a gift of God, but the gift of God. See also John 3:16; Romans 6:23. This description would then imply that these apostates had some kind of experience with the Lord Jesus, without being regenerated which is not impossible. Being within the congregation of His called-out-ones they would have certainly known the Lord Jesus through experience in some way. These are not people who have come to church one day, “accepted” Jesus and then went into the world. Rather, these people were steeped into Christ’s religion and then apostatized. They had seen Christianity confirmed in various ways before their eyes and yet still choose to abandon their profession and reject the Christian faith and its founder, Christ the Lord.
For the Holy Spirit being the gift of God, Acts 2:38 is primary where the Holy Spirit is said to be the gift given by God to those who repent. He is heavenly, because He comes from heaven – He comes from God and is God. John Owen humbly defends this view:
It is, as many judge, the person of Christ himself in that place which is intended. But the context makes plain that it is the Holy Ghost; for he is the “living water” which the Lord Jesus promiseth in that place to bestow. And so far as I can observe, δωρεά, “the gift,” with respect unto God, as denoting the thing given, is nowhere used but only t...