Reading the Bible as a duty or to prepare a message isn't going to do us any good personally, if we remain the same afterwards. But when we look at it as at a mirror that shows us what God thinks about us, it gives us an opportunity to cleanse ourselves and to become more like Him (2Co.3:18). It is when we allow God to show us the dirt in out life that we can seek Him for cleansing and become better people, more like Him (Jas.1:23,24).
But the blindness that is over our flesh (old sinful life) (Ep.4:18) does not disappear easily unless we crucify it (Ga.5:24) and constantly put it to death through the power of the Spirit (Ro.8:13). All of us are blind to a greater or lesser extent about the sins and mistakes we commit. We are unable to see them till the light of God shines into our heart, and that will happen only when we open ourselves to His light and are willing to humbly acknowledge them and change.
Look at one example from the life of Moses. There was a time when God asked him to strike a rock with his rod for water to flow out (Ex.17:6). But the next time he was asked only to speak to it (Nu.20:8). But Moses was angry and frustrated with the people this time and instead of just speaking to the rock he struck it with his rod, calling them rebels (vv.10,11). God still gave water to the people. But He reprimanded Moses for not honouring Him before the people and told him that he would not be able to take the people into the Promised Land (v.12).
We can see clearly that even though the people were disbelieving God's ability to provide them water, it was for Moses' own proud behaviour that he was disciplined. But the sad thing is that he could not see his own fault even later. In De.4:21, which was his closing message to the people before he died, he said that it was because of them that God was angry with him!
No, God is not like that. He will not punish anyone for someone else's sins (Ez.18:20). How could He be angry with Moses for the people's sins? But Moses couldn't see his own fault here because his anger was still focused on the people's unbelief.
Now we cannot look down on Moses because we have been guilty of the same wrong attitude many times in the past. We may thinking in the same way many times even now without realising it. This is our old human nature. And that is why we need to make special efforts to look at the mirror and see in God's light where we have gone wrong, even when we can easily see the faults of others. That is the only way we can make progress. How sad it will be if we go down to the grave imagining great things about ourselves when God has seen so many sinful and foolish things we have done without even acknowledging them?
God is forgiving, as He was to Moses. What Moses couldn't do was to lead the people into the Land, though he himself entered it at the time of Jesus' transfiguration. But what we lose is our opportunity to cleanse ourselves and become more like Jesus.