D&C 45
I notice that the opening of this section is very similar tot he opening in section 39. I believe that this is because this was given not long afterwards in a new location (Kirtland, Ohio rather than Harmony, Pennsylvania). The Lord wanted people in both places to have that doctrine before they had a compilation of the revelations.
The fig tree produces fruit before it produces leaves. When it produces leaves we know that summer is near. Christ cursed the fig tree by the road because summer had come and it had not born fruit. We must be fruitful before we see the last evidence that summer is here or else we stand to be unprepared for the tribulation that will mark the opening of that summer season.
When Christ comes to the Mount of Olives to rescue the Jews they shall hail Him as their long awaited savior without knowing who He is. They shall then ask about His wounds and He will declare that He is Christ. When they hear that they will lament the centuries when others had that knowledge but they and their parents refused to see it.
Then, after the calamities, shall the earth be given to the meek who had wisely prepared as they were instructed. Those, whether in or out of the church, who will not join in the destruction and fighting will be welcomed into Zion. Those who participate in that wickedness will fear Zion.