To trust someone or something we look at their track record.
What does past performance/behaviour indicate? This directs our current response and our own behaviour and actions towards them. Then we can consider, what does this imply for our future? Is this person/company/thing going to be something I can rely upon? Something that will be of benefit in forthcoming years?
Isaiah wrote this passage(Isaiah 25:1-4)
O Lord, you are my God;
I will exalt you; I will praise your name,
for you have done wonderful things,
plans formed of old, faithful and sure.
2 For you have made the city a heap,
the fortified city a ruin;
the foreigners’ palace is a city no more;
it will never be rebuilt.
3 Therefore strong peoples will glorify you;
cities of ruthless nations will fear you.
4 For you have been a stronghold to the poor,
a stronghold to the needy in his distress,
a shelter from the storm and a shade from the heat;
for the breath of the ruthless is like a storm against a wall,
From my experience, I know that I can trust my parents. They have looked after me, loved and supported me even when I've made mistakes. They have shown that they are reliable, strong and loving.
So, I trust them.
I know I can depend on them in forthcoming years.
To me, this is what the above passage is saying, that 'wonderful things', 'plans of old', acts of the past, can be built upon so that we can have security for the future. Those that have been reliable before are those people that we can trust now and for the future.
We should acknowledge and 'exhalt' those that have proved their worth in our lives, we should recognise and value them as Isaiah does. His current behaviour depends on his past experience. He says he 'Will exhalt'. He chooses to because of the 'wonderful things' he has seen God do. His present mindset and actions have been formed by reflecting on what has influenced his life.
I know that some people have some awful experiences in their past, that's true and unavoidable. But, surely there must be some 'wonderful things' too? What are they? And how can we each appreciate them?
What is it that you want to build your life upon?
Isaiah lived in a time of political unrest, he saw and experienced his country at war. With those in power trusting in other corrupt nations for help. Isaiah was in the position to advise those in power, and he did so. He did not trust in rulers or so-called world leaders, but chose to trust God, even though he clearly had some kind of relationship with important leaders.
Leaders often make plans, plans for what may seem the best at the time, but Isaiah saw that God had, 'plans formed of old, faithful and sure'. God's plans are well thought out, forward looking and reliable. They are not 'in the moment' ideas, but considerate, deliberate plans. Isaiah saw that God's track record was good. His plans had worked before, so he could trust them as 'faithful and sure'.
Just as we can.
You see, God hasn't changed, and that's a good thing! Isaiah understood that though God's plans are formed 'of old', they are relevant and dependable, considered, thought through.
This shows God's steadfastness, He doesn't change, He is always a good base to rely on.