26:1
“In that day” is a technical term referring to future days (24:21; 25:9; 27:1)

The word translated “ramparts” is the word khel which likely refers to the sloping fortification of dirt and rock built against the wall (also called a glacis, see Ashkelon's glacis or khel against the city wall HERE.)

26:2
Opening the gates of the city for the righteous is a welcoming believers with faith and righteousness to enter this fortified city. The opposite is true also. Those without trust in the Lord will not be able to access this place of peace and protection.

26:3 “perfect peace” is literally “peace, peace” in the Hebrew. The repeated double word makes the meaning absolute.

It is important to understand the phrase referring to “those whose minds are steadfast.” The word “mind” or “thoughts” is from the Hebrew word yester which communicates the idea of “outlook on life,” “worldview,” “point of reference,” or “frame of mind.” The opposite of this mind would be James’ “double minded man” in James 1:6-8 and Jesus’ man who serves two masters in Matthew 6:24. Without this renewed view of life that includes a comprehensive understanding of the Lord there is no peace.

But let him ask in faith, with no doubting, for the one who doubts is like a wave of the sea that is driven and tossed by the wind. 7 For that person must not suppose that he will receive anything from the Lord; 8 he is a double-minded man, unstable in all his ways. - James 1:6-8

No one can serve two masters, for either he will hate the one and love the other, or he will be devoted to the one and despise the other. You cannot serve God and money. - Matthew 6:24

"Man will believe anything, as long as it's not in the bible."
- Napoleon Bonaparte

• Angels are mentioned in thirty-four of the sixty-six books in the Bible. These thrity-four books cover the full spectrum of time from Genesis through the Jewish return from Babylon and from the announcement of the birth of Jesus through Acts.

• Angels appear to have been created before the universe.

• Angels have freewill and at some point in the past some choose to rebel against God.

• Angels can interact with the physical world and are used by God for a variety of reasons including communication, judgment, council, assistance for believers, and more.

• Angels, both fallen and holy, are highly organized and have specific job assignments.

• The appearance of the Angel of the Lord in the Old Testament is a theophany or an appearance of the second member of the Trinity.

• Satan is an angel from the class of angels called cherubim who rebelled against God and is called by several names including the prince of the power of the air and the god of this world.