"the Holy Spirit, who is "the one who is holding [the antichrist] back"
I have heard the 'restrainer' being explained this way - also have heard that it is Michael, the Archangel, which sounds more logical to me. Regardless, scripture does not say exactly who the 'restrainer' is.
"this time is also referred to as "the time of Jacob's (a.k.a. Israel) Trouble, meaning it concerns the nation of Israel and not the church."
Who is Israel?
If you properly discern and apply scripture one must conclude that Israel includes both Jews and Gentiles. There is only one God, one faith, and one baptism. As Gentile believers, we have been grafted in to the tree (as the tree has both natural and wild branches) and are now the offspring of Abraham and heirs to the promise.
Read Ezekiel 37:15-28
The word of Yahweh came to me saying, Now you, Son of Man, take for yourself one stick and write upon it, "For Judah and for the children of Israel, his companions; and take another stick and write upon it, for Joseph, the stick of Ephraim, and for all the house of Israel, his companions: And join them into one stick: and they shall become one in thine hand...I will take thh children of Israel from among the heathen, whither they be gone, and will gather them on every side, and bring them into their own land: And I will make the ONE NATION in the land...so shall they be my people, and I will be their God.
This scripture describes the two houses of Israel. One is Judah, the Jew, and his companions and the other is the house of Israel (Ephraim) and his companions. When the Lord returns to set up his kingdom on earth, there will be twelve gates in and out of the city - for the twelve tribes of Israel. We will all enter through one of those gates, because as believers (companions) we have become one with Israel.