Why does St. Ignatius the Theophorus call the Church “a congregation of thanksgiving and praise”?

Because in the Eucharist, the Church is manifested in two ways. The first way is through love, purity, unity, fellowship in immortality, along with joy and praise. The second way is by resisting the devil and conquering him. St. Ignatius the Theophorus says, “Take heed, then, often to come together to give thanks to God, and show forth His praise. For when you assemble frequently in the same place, the powers of Satan are destroyed, and the destruction at which he aims is prevented by the unity of your faith.”¹⁰⁹⁴