Warring parties often accuse each other of being demons. Those who opposed Jesus accused him that his words and deeds were demonic! Jesus told them that his power came from God.
All down the centuries the powers that be, who feel threatened by Christian teachings and deeds, have accused the Church of all kinds of "demonic" things. The Church never counter-accuses. Instead, the Church has been winning victory after victory; these victories are built on the power of the Spirit of God, who guides and protects the Church.
On the personal front, Jesus is cautioning us to be on our guard against evil at all times. We are not to be complacent, lest we suffer serious defeat by the Evil One. Instead, our day-to-day little victories over evil can be built up for the strengthening of the larger community for the greater good of humankind.
By ourselves we do not have the strength to fight evil. Jesus teaches us to pray to the Father and ask to be kept free from temptation.
Our Father in Heaven, lead us not into temptation, but set us free from evil.