Master, Moses wrote unto us, If a man’s brother die, and leave his wife behind him, and leave no children, that his brother should take his wife, and raise up seed unto his brother. Now there were seven brethren: and the first took a wife, and dying left no seed. And the second took her, and died, neither left he any seed: and the third likewise. And the seven had her, and left no seed: last of all the woman died also. In the resurrection therefore, when they shall rise, whose wife shall she be of them? for the seven had her to wife. And Jesus answering said unto them, Do ye not therefore err, because ye know not the scriptures, neither the power of God? For when they shall rise from the dead, they neither marry, nor are given in marriage; but are as the angels which are in heaven. And as touching the dead, that they rise: have ye not read in the book of Moses, how in the bush God spake unto him, saying, I am the God of Abraham, and the God of Isaac, and the God of Jacob? He is not the God of the dead, but the God of the living: ye therefore do greatly err.
(Mark 12:19-27)

Then read this:

Brethren, I speak after the manner of men; Though it be but a man’s covenant, yet if it be confirmed, no man disannulleth, or addeth thereto. Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ. And this I say, that the covenant, that was confirmed before of God in Christ, the law, which was four hundred and thirty years after, cannot disannul, that it should make the promise of none effect.
(Galatians 3:15-17)

In these passages, Jesus and then Paul expound on doctrine based on what would (at first) seem to be insignificant details. In the first example, Jesus establishes the fact (before the unbelieving Sadducees) that there is a resurrection by pointing out that God said to Moses, “I am the God of Abraham, and the God of Isaac, and the God of Jacob”. Then, in the second example, Paul reveals that in Genesis 22:18, God was referring to Jesus Christ and not to Isaac and his descendants because the singular Hebrew word for seed was used and not the plural.

So think about this the next time you hear someone questioning the precision of the Word of God. And also tell your children that, yes, grammar is important.