A. What do you think about Jeremiah 29:11?
Jeremiah 29:11 applies to Israel.
There is a difference in covenants between what Israel received and what the assembly of saints received.
The Mosaic covenant, given to the children of Israel, promises land as an inheritance. It also promises peace, good weather for growing food, health, and prosperity in that land. These promises from the Mosaic covenant are conditional based on obedience to the Mosaic covenant. If the people are not obedient, they could lose all of these promises; food, health, prosperity, peace, and finally scattering/expulsion from the land. These were punishments. So, when the children of Israel were disobedient, we find the prophets telling the people to repent to avoid the punishments, and if they repent, God will do as He promised, restore them to the land, and grant them peace, food, health, prosperity, in the land.
The New Covenant promises one main inheritance, the kingdom of God. Since this is a unilateral covenant, all of the promises come thru the completed work of Jesus. This promise is not dependent on the actions of the people but purely on God and Jesus completed work.
The promises to the nation(People) of Israel in the Mosaic covenant are all temporal and physical while the promises to the Saints are eternal and spiritual. Israel is promised land and food, peace and prosperity while the Saints are promised that God would take care of their needs, peace which passes understanding (spiritual), joy (spiritual fruit), conformity to Jesus (spirtual), the Holy Spirit (spiritual), the Kingdom of God (eternal).
B. What do you think of the quote above from reasons.org?
I think they are correct.