"We are a fragrance of Christ to God among those who are being saved and among those who are perishing" (2Co.2:15). We do want to be like that, and we wish we were more like that than what we really are! So, is this a statement we can simply accept for a fact or make ourselves believe? Aren't statements like this to be taken as personal challenges for us individually? "God has not given us a spirit of timidity, but of power and love and discipline" (2Ti.1:7). This is what God wants us to have, but have we actually come to experience this in reality? Will they actually become a reality if we go on confessing or declaring them? These are examples of how we can actually live in spiritual poverty but convince ourselves or make ourselves believe something else.
Spiritual growth means not merely to know more Scripture or to be very familiar with the external practices of religion, such as a regular 'quiet time', prayer, church attendance even taking part in ministries. It means to be transformed in our spirit to think more like God, share His values, doing what He wants, and counting everything else as being less important. If this is happening, verses such as the above will also become more and more of a reality in our life. But if this is not happening, we will only be deceiving ourselves if we make ourselves believe such statements about us.
On the other hand, we can believe whatever God says or promises, just because His word says so. We can believe He will never leave or forsake us (He.13:5). Once He has forgiven us, He will never hold our sins against us any more (He.8:12). Etc. If we don't believe what God says, we become actually unbelievers in those instances.
In order for the holy God to be able to accept us sinful people with all our imperfections even after we have repented from our sins and trusted Jesus as our Saviour, He credits the righteousness of Christ to us. Now He can deal with us as if we were righteous people. But in reality, we have not become righteous yet but are going though a process of sanctification by which little by little we are being transformed. If we were to hold to this imputed righteousness and make ourselves believe we are actually righteous, we are under a great deception. Check with reality. When we do that we sadly find many things in us that are not righteous, and then we learn to cry out to God, "Wretched man that I am! Who will set me free from the body of this death?" (Ro.7:24). Then God will help us to experience a greater deliverance from the hold of sin in our life and to actually become more like Christ.
If we don't make this difference in our mind, we can fool ourselves with eternal consequences by declaring statements from the Bible telling us how we ought to be. We must check such statements with our actual life and see how much it is true in us.
It is sad if we are living in 'doctrinal bubbles', isolating ourselves from reality. One day those bubbles will burst.