Atheists and followers of false gods deny miracles, or they deny that God concerns Himself with human affairs. Christians, on the other hand, insist both that God regularly involves Himself in human affairs (indeed is sovereign over them, as we will see in the theology of history that unfolds in the following books) and that the highest possible good of man is to be personally united to this God of history. Both of these truths are demonstrated by means of the miracles in Scripture.
Some hear these things and come to the conclusion that God must be worshiped only by "a pure mind and upright will." This misses the point, since the sacrifice God truly desires is that of a repentant heart that is a sign of the true spiritual sacrifice of the cross. "So, too, when we offer sacrifice, we know that visible sacrifice should be offered to no one but Him to whom we ourselves, in our hearts, should be the invisible sacrifice."
In this, Godly men and angels are alike--we worship God alone and do not divert that worship to any other creature, not even other powerful spiritual beings.
All our dedication, all our "sacrifice", to God is possible only through the work of God--namely through the work of the God-Man Jesus Christ. He is the only who who can receive sacrifice, make a sacrifice, and be the sacrifice simultaneously. He receives sacrifices "In His character as God, He receives sacrifices in union with the Father, with whom He is one God; yet He chose, in His character as a slave, to be Himself the Sacrifice rather than to receive it." And he makes the sacrifice as well: "thus it is that He is both the Priest who offers and the Oblation that is offered."
And so, the Christian life should be daily shaped by this sacrifice: "it was His will that as a sacrament of this reality there should be the daily sacrifice of the Church, which, being the Body of Him, her Head, learns to offer itself through Him." In one sense this means communion, when we see over and over the picture of what Christ has done for us on the cross and the reminder that it ought to affect and shape our lives and the symbol that as those covered by the blood of Christ we are now set apart for holy living from the rest of the city of man. But this does not just mean that, especially in the context of the discussion of true sacrifice in the preceding chapters. It means also that every aspect of our lives ought to be lived as sacrifices in the shadow and reflection of Christ's true Sacrifice. That we have been bought ought of our sin and restored to a relationship with God--the one union which leads to true happiness, as we saw in chapter 18--ought to seep through our whole beings and shape us, over time, into new creations. We ought increasingly to be mortifying sin and growing in the Fruit of the Spirit. (If you want an excellent book on the former, I recommend either John Owen's difficult Mortification of Sin or Kris Lundegaard's summary of that book The Enemy Within; for the latter Owen's difficult Communion with God or Jerry Bridges' Practice of Godliness are both excellent.) As we mature, every part of our lives should become sacrifices reflective of the Sacrifice of Christ on the cross.
Whatever power demonic forces may have in opposition to this pursuit of holiness on the part of believes is power only given 1) by God to these demonic forces 2) for our own good and 3) for His own glory. That is,
1) "The power delegated to the demons at certain appointed and well-adjusted season"--God grants this power. Demonic forces can do nothing of their own free will, as we have seen already, God is sovereign even over evil.
2) "This power is found to be not merely harmless, but even useful to the Church, completing as it does the number of martyrs, whom the city of God esteems as all the more illustrious and honored citizens, because they have striven even to blood against the sin of impiety;" That which the demons intended for evil is turned to good by the Divine plan of God for the growth and advancement of His church.
3) "Our heroes, if we could so call them, overcome Hêrê, not by suppliant gifts, but by divine virtues." The triumph of the church over demonic powers comes not through any inherent strength in us, but by the Divinely given gifts. This suggests that the final glory for this victory comes not ultimately to us, but to the Source and Giver of those gifts, Jesus Christ. Not that we get nothing, of course! In the union with God which He bought for us we receive eternal joy and delight in His presence, while He gets all the praise for having accomplished this great work!