“He who dwells in the secret place of the Most High Shall abide under the shadow of the Almighty. 2I will say of the Lord, “He is my refuge and my fortress; My God, in Him I will trust. (Psa 91:1-2)…
No evil shall befall you, nor shall any plague come near your dwelling; 11for He shall give His angels charge over you, to keep you in all your ways. 12In their hands they shall bear you up, lest you dash your foot against a stone. 13You shall tread upon the lion and the cobra, the young lion and the serpent you shall trample underfoot. (Psalm 91:10–13)
Today, in addition to finding courage in these words, we recognize this song of protection as one that Satan used in an attempt to get Jesus to jump off a pinnacle of the temple… to prove (and possibly force) the hand of God’s protection (Matt 4:5-6)
Since Jesus responded with another text saying, “It is also written, do not put the Lord your God to the test” (Matt 4:7), it’s clear that these words, like the rest of the Bible, can be quoted with faith and profit, or with presumption and loss.
As so many of us have acknowledged in these conversations, no individual text of the Bible stands by itself. Psalm 91 is no different. It must be interpreted in light of all that precedes and follows. In this case we only have to go back a few statements to find another perspective:
The days of our lives are seventy years; and if by reason of strength they are eighty years, yet their boast is only labor and sorrow; for it is soon cut off, and we fly away. (Psalm 90:10).
So how are we to understand and count on the protection we find in Psalm 91? Certainly it is not our only assurance of God’s protection. Much later in the Bible the author of Hebrews writes,
“Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee. 6 So that we may boldly say, The Lord is my helper, and I will not fear what man shall do unto me.” (Heb 13:5-6)
Seems to me that there is a way of claiming Psalm 91 for ourselves, if we first reflect on how it was ultimately fulfilled in Jesus. After seeing how he rested in the shadow of his Almighty Father, I take it that we can say in faith– rather than with presumption, ‘As we rest in the presence and purposes of our God, no one, can keep us from being, saying, or doing whatever our Lord wants us to be, say, or do… on his terms of safety rather than our own. ”
In other words we can claim the kind of loving protection that this Psalm talks about as long as our trust extends to anything our Father lovingly and wisely allows into our life.
In this regard, seeing how the 91st Psalm is fulfilled in Christ provides a good backdrop for the Heidelberg Catechism which asks:
“1. Question. What is your only comfort in life and death?”
And answers: “That I am not my own,  but belong with body and soul, both in life and in death,  to my faithful Saviour Jesus Christ.  He has fully paid for all my sins with His precious blood , and has set me free from all the power of the devil.  He also preserves me in such a way  that without the will of my heavenly Father not a hair can fall from my head;  indeed, all things must work together for my salvation.  Therefore, by His Holy Spirit He also assures me of eternal life  and makes me heartily willing and ready from now on to live for Him.  (The catechism uses the following corresponding texts as support for this answer)
 (1Cor 6:19,20);  (Rom 14:7-9)  (1Cor 3:23) (Tit 2:14);  1Pet 1:18;19) (1John 1:7) 1John 2:2);  (John 8:34-36) (Heb 2:14-15) (1John 3:8);  (John 6:39-40) (John 10:27-30) (2Thess 3:3) (1Peter 1:5);  (Matt 10:29-31) (Luke 21:16-18);  (Rom 8:28)  (Rom 8:15-16) (2Cor 1:21-22) (1Cor 5:5) (Eph 1:13-14)  (Rom 8:14).”
This is a bit long. But I think it’s important to consider all of this in our ongoing conversations of how to hear the Bible as the Word of God. Seems to me that if we don’t show such care, the most wonderful assurances of Scripture can result in great disillusionment and loss of faith.