It must be true because I felt it, I felt the presence of God in the worship service, and I felt the moving of the Holy Spirit. I used to think that. Unaware, I was conditioned to believe some doctrines to be true because I experienced it myself. Tell you what, that situation is recipe for depression.
As you get older, you find that what you feel is not always true, and your strongest enemy within you is your emotion. If you have been conditioned that "feeling" great means you are into God's will, when depression hits, guess what? You go down the tubes so fast you need a parachute.
When I am depressed, I now realize that what I need at that time is not to feed my emotion, besides, depression is like that, it refuses to be comforted by whatever is good. Providentially this is where the divine service, ie the formal liturgy has helped me. Because there you will find that your mind is being drawn away from you, at least for a brief moment, you are being helped to not focus on what is inside you but to focus on what is outside you. That I believe is what I need when I am depressed, something that will bring me out from my mind which is going 200 miles per hour with anxiety and what have you, to the truth that never changes. You need truth that is unchanging, that is there whatever your feelings might be - be it good, nice, warm feelings or not. That is God's Word and God's Done Deal in Jesus - the Cross. Whatever promotes that, that is what I believe we need, and a liturgy that is peppered by God's Word is the most useful tool to have and use.
Then there is also the aspect of creeds and confessions. I now think that creeds and confessions must have been practiced and used by the early Christians because these creeds have the effect of limiting the domain of your thinking and imagination. It is kind of a fence or a border to which you can relate too in your private moments of reflection, as you are lost in your own thoughts and imaginings, it will tell you or pull you back from where you have strayed. And by George, we have plenty of that, our sinful nature talks to us and lies to us 24 X 7 . We can manufacture novel ideas and teachings without realizing they are heresies.
Of course there is no comparison, absolutely no comparison, with Scriptural passages being recited and confessed. That should be a habit too specially the passages that promises us forgiveness/salvation. Scripture is there, it is outside you, it has no bearing on how or what you feel about you or about God at all. The Creeds however convey the truth of Scripture's teaching in summary form.
For me now, the creeds although they can be mechanically recited, should not be. Rather as it is recited, it ought to be reflected on. They are meant to convict and comfort us by the truth those creedal lines convey. It normally starts with I believe not with I feel.
Amazingly when you are challenged again and again by what you say you believe (and do you really), your feelings change. I think it starts getting comforted by the truth that Jesus loves you by dying and rising from the dead -- for you, your sins. That is good news one should never get tired of hearing and believing.
1 Timothy 6:12
Fight the good fight of the faith. Take hold of the eternal life to which you were called and about which you made the good confession in the presence of many witnesses.