They cannot even die anymore,
because they are like angels,
and are sons of God,
being sons of the resurrection.
The Sadducees, who did not believe that the dead would rise again, had asked the Lord Jesus a trick question. They came up with an imaginary woman who married the eldest of seven brothers.
One after another died, and according to the law of Moses the next one always married this woman. Then whose wife will she be in the resurrection?
The Lord answers succinctly, that there will be no more marriages in the resurrection, for the resurrected will be like the angels.
Of course, the resurrected devotees will not be like the angels in everything. The human remains a human being for all eternity. But in this they are like the angels, that there will be no more marriages.
The root cause of marriage lies in posterity.
With some exceptions, a new generation thrives out of practically every marriage. And this is no longer necessary, because no more people will fall away (There is no death anymore).
Partly because of this, the eternal community is purified and purely spiritual, as with the angels.