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Most often" means not all or not without exception. I'm the exception as I am not a dispensationalist. In fact, I've debated dispensationalist here and shown how they are remiss about the OT prophecies too. You are also remiss about the context of Genesis 22:18, from where Paul cites in Galatian 3:16. The antecedent verses in Genesis is:
And said, By myself have I sworn, saith the LORD, for because thou hast done this thing, and hast not withheld thy son, thine only son: That in blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore; and thy seed shall possess the gate of his enemies. Genesis 22:16-17
The term “seed” has both a singular and collective sense, the latter being
a body of individuals, also substantiated in Genesis 13:15-16. That is why Paul uses the collective sense in the last verse in Galatians 3.
And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise. Galatians 3:29
We find the same two senses in Isaiah 54:3, except in the untenable perception of Replacement theology. The “seed” is initially Christ and again, collectively Ephraim.
Gen 3:15 And I will put enmity between thee and the woman, and between thy seed and
her seed; it shall bruise thy head,
and thou shalt bruise his heel.
Mat 1:1 The book of the generation of
Jesus Christ, the son of David, the son of Abraham.
Mat 21:33 Hear another parable: There was a certain householder, which planted a vineyard, and hedged it round about, and digged a winepress in it, and built a tower, and let it out to husbandmen, and went into a far country:
Mat 21:34 And when the time of the fruit drew near, he sent his servants to the husbandmen, that they might receive the fruits of it.
Mat 21:35 And the husbandmen took his servants, and beat one, and killed another, and stoned another.
Mat 21:36 Again, he sent other servants more than the first: and they did unto them likewise.
Mat 21:37
But last of all he sent unto them his son, saying, They will reverence my son.
Mat 21:38 But when the husbandmen saw the son, they said among themselves,
This is the heir; come, let us kill him, and let us seize on his inheritance.
Mat 21:39 And they caught him, and cast him out of the vineyard, and slew him.
Mat 21:40 When the lord therefore of the vineyard cometh, what will he do unto those husbandmen?
Mat 21:41 They say unto him, He will miserably destroy those wicked men, and will let out his vineyard unto other husbandmen, which shall render him the fruits in their seasons.
Mat 21:42 Jesus saith unto them, Did ye never read in the scriptures,
The stone which the builders rejected, the same is become the head of the corner: this is the Lord's doing, and it is marvellous in our eyes?
Mat 21:43 Therefore say I unto you,
The kingdom of God shall be taken from you, and given to a nation bringing forth the fruits thereof.
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