The seventh church is Laodiciea. The salutation affirms Jesus as God's word, the main expression of who God is, and what he is like.
He knows their walk. He describes it as lukewarm. His preference would be hot: faithful, pursuing his mission, and focusing on knowing and obeying God's word. But he would rather that they were cold, so he could work in them to move them in a positive direction.
They are lukewarm -- not against God, but not really pursuing God -- because they perceive themselves as having made it. They are the ones, who have it all figured out. And that perspective just increases pride in their hearts.
They believe they have no needs, when in reality, they are extremely needy. They are needy, because they do not pursue God, who is the one who fulfills, and meets all needs.
God reminds them that he has the cure for their needs, and he seeks to correct those he loves. They may experience trouble. And he affirms his willingness, and readiness, to unite with them, claim them as his own, and pursue relationship with them.
The overcomer is the one, who returns to relationship with him. He will rule with him. As Jesus conquered sin, and injected life into the world, they will experience that life.