The pride comes from the self-rghteousness inherent in the Protestant OSAS doctrine. We may believe, but we are still subject to deceit by the devil and his temptation, and we are still capable of evil.
If satan went after Christ (not knowing He is God), trying to tempt Him, what makes you think we are immune?
Thou believest that there is one God; thou doest well: the devils also believe, and tremble. James 2:19
Therefore rejoice, [ye] heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea! for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time. Rev 12:12
And when the thousand years are expired, Satan shall be loosed out of his prison, And shall go out to deceive the nations which are in the four quarters of the earth, Gog and Magog, to gather them together to battle: the number of whom [is] as the sand of the sea. And they went up on the breadth of the earth, and compassed the camp of the saints about, and the beloved city: and fire came down from God out of heaven, and devoured them. And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet [are], and shall be tormented day and night for ever and ever. Rev 20:7-10
Blessed [is] the man that endureth temptation: for when he is tried, he shall receive the crown of life, which the Lord hath promised to them that love him. Let no man say when he is tempted, I am tempted of God: for God cannot be tempted with evil, neither tempteth he any man: But every man is tempted, when he is drawn away of his own lust, and enticed. Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death. Do not err, my beloved brethren. James 1:12-16
What if satan knew very well that Christ is God, and that is precisely the reason he "went after" Him in the first place, the primary motivating factor?
At any rate, that would be my expectation. Satan's entire mission in everlasting death is to "trash God." He already knows he "can't win." So he is determined to take down into eternal perdition with him as many of God's beloved creatures as possible, just for sheer ungrateful, ungodly, and unregenerate spite.
And if satan finds that God lives in the soul of any particular man by His Spirit and Grace, then that particular person would present an interesting target from his point of view.
And so you raised the issue of: How do we know, when in our devotions, that the Presence we experience isn't satan himself, deceiving us?
It is a very good question to bear in mind. Let us for the sake of argument allow that there are spirits effective in the ordinary world of human experience, many if not most of which bear ill will towards human beings.
That granted, still the human being has to give them a niche to slink in through before they can do any real damage. From satan's point of view, he gets the best traction out of the perpetrators of the Seven Deadly Sins: Pride, envy, anger, sloth, greed, gluttony, and lust....
Add to that list: Spiritual pride (your recommendation); arrogance; narcissism; inordinate desire for anything that is not God....
In God alone is the Logos, Truth -- thus final authority in this world and the next.
All praise and glory be to His Holy Names!
God bless you for writing, dear kosta50!