"Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusteth in thee." Isaiah 26:3
Note: Before you read this I want you to know that over time all of us question our faith and to what extent we are actually reaching God with our prayers and petitions. I get it if you are not at perfect peace and if you are feeling the stress and the strain of the world, issues, mistakes, indiscretions, overwhelming conditions. You are going to go through things and it will not all be pleasant. There are times when you just want to throw good theology out and just run with your your feelings, let go, give up, give in, etc. What I have concluded is that there is no better way to go through all the imperfections associated with this life than with an active, personal relationship with God. It always turns out in the end that God/God's instructions and prophesy as written in the Bible is always right and just. Everything with God is better than anything without God.
First of all if you are not interested in perfect peace, there is no advantage to investigating the Word of God concerning having perfect peace. Most of the scriptures are for contemplation and once that contemplation has taken place then the connection between God and man via the Spirit of God can take place. Spiritual truths can only be understood and utilized in direct relation to the degree of involvement that we give it. In other words, if you read a verse of scripture and understand it, and then make it the truth that resides in your heart and you use it as a guideline for all future events in your life, that truth can and will get fully utilized by you to fulfill the purposes of God in/by you.
If on the other hand you only gloss over the scripture and say, "it's all Greek to me," you will not possess the truths contained therein for use and you will not be aligning your will with God's will for the purpose of fulfilling the purposes of God in/by you. The word stayed means; to lean on, lie hard upon, rest upon, stand fast to and sustain. Stayed isn't changing your mind all the time. Stayed is your mind made up. It means that when conditions are not favorable and situations are seemingly out of control, and even if it looks like the bottom is/has fallen out, you hold fast to the truth that is in you. Even if the circumstances say it's not true, you hold fast. Even when others are falling away from the principles that you have come to know as godly, you hold true.
Perfect peace takes effort. I know, effort and hard work and diligence and long-suffering aren't popular trends, but they are biblical trends. I won't belabor the issue, but I do want to say, living a wishy-washy, candy-coated, watered-down, on and off relationship with Jesus is really empty and futile. You really can't have the best of two worlds and somehow think that you can separate one part of your life from another. You are a whole person and every input and output that goes into you and out from you, is you. Learn not to be satisfied with the status quo and you might find that the way of God is really far superior to the way of the world, no exceptions."