Many, many more knowledgeable and experienced preachers than me, a layman, have had difficulty with interpreting this passage, especially the part referring to 'a god of fortresses' and who that god may be. My intent is not to interpret it, because I am not qualified. I do want to simply relate what it made me think of when I read it.
Fortresses we know from the bible are also known as 'Strongholds' which "are erected by our wounded souls to protect us and to keep pain and rejection out. When we were brokenhearted, we went into self-protection mode," writes Carlotta Waldmann. And when we are protecting self, it is easier to sink into self-delusion, or to accept the lie that satan offers. And the first brick in the stronghold is laid.
Now, God's intent is to draw us to Him, and for us to become so close to Him we are "part of His body" (after confessing our sins and asking for forgiveness). Satan's strategy is separation, to separate us from the truth, from Jesus and from the knowledge of our sins. To keep us from being absorbed into the fold and sealed with the Spirit. If you are stuck inside a fortress, you certainly are separated! Indeed, when satan is successful it results in a person eternally separated from God, in hell. That is the war: are you available and free to be drawn to Christ, or are you stuck behind a fortress?
One way satan separates us is through building strongholds (fortresses) in our mind. Paul defines fortresses:
"For though we live in the world, we do not wage war as the world does. The weapons we fight with are not the weapons of the world. On the contrary, they have divine power to demolish strongholds. We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ." 2 Cor 10:3-5 (NIV)
Paul says that those old fortresses of arguments and pretensions and speculations (words, we note) are "demolished" through words. The Word of Truth. Thoughts held captive. Paul urges we speak boldly: "I, Paul, who am "timid" when face to face with you, but "bold" when away! (verse 1b)
Now, in Daniel, the god of fortresses to whom the antichrist pays homage is "constructed" through words and he will prosper until the indignation is finished, for that which is decreed will be done. He will show no regard for the gods of his fathers or for the desire of women, nor will he show regard for any other god; for he will magnify himself above them all. But instead he will honor a god of fortresses, a god whom his fathers did not know; he will honor him with gold, silver, costly stones and treasures." Daniel 11:36-38
And: "By smooth words he will turn to godlessness those who act wickedly toward the covenant, but the people who know their God will display strength and take action." Daniel 11:32
Daniel isn't saying that the action to be taken is to take up a sword and slice every godless soul you see. Nor does it mean build churches, fight, or claim territory in some sort of territorial war. It is through words that the action is taken. It is by speaking the truth of Jesus. Paul says that the destruction of fortresses is via words and Daniel tells us that the god of fortresses is constructed through the antichrist's words. Do you still believe that "sticks and stones may break my bones but words will never hurt me"? They do hurt.
First and foremost they hurt yourself. They allow satan a foothold and every wrong word and every wrong thought is a brick. Another brick in the wall. A cathedral, large as it is, is built brick by brick. So is a fortress in your mind. Every thought not taken captive is one more brick that edges its height inexorably to the top, where your soul, imprisoned, may not fly and your choice to be eternally separated from God is honored.
Christian, are you trapped in a stronghold? Even the tiniest one is the start of something big. Demolish that fortress and serve not the god of fortresses but the One True God, in whom there is no condemnation, but only love. Take a mental sledgehammer and speak firmly to satan, pulling down his speculations and arguments with the simple truth, that he has no authority over you. That you are a child of God, part of Jesus' body, and guided by the Holy Spirit who is sealed within you. Pray these words, speak these words, say them to others who need to hear them. Fortresses are built with words, the antichrist serves a god of fortresses and speaks smooth words. But they can be demolished with words too. Are you ready to speak them? All Christians are needed now to be ship-shape for the battle.