Ecclesiastes 10:10 (NKJV)
If you have ever tried to cut something with a dull knife or scissors, you know that it can be hard to do, and even frustrating. The same thing applies to cutting down a tree with an ax or a chainsaw. If the tool you are using to cut something with is dull, you may be able to cut what you need to, but it will not be an easy process. The best thing to do is to make sure the tool being used is sharp and ready for use, if not, then the tool needs to be sharpened to be effective.
Things can become dull through simple everyday use, and this is why things need to be sharpened on a regular basis. It is not a bad thing if a tool becomes dull, but it is foolish not to then sharpen that tool so that it can produce the desired results. As Christians, it is easy to become "dull" spiritually, just through living our life every day and doing things that need to be done. Sometimes Christians become spiritually dull without realizing it and it then seems that living the Christian life and serving God becomes very difficult.
If we really want to be the kind of people that God can use in His Kingdom the way He wants to, we have to be sure that we are having a regular time of reading and studying the Bible, as well as a regular time of praying and talking to God. Doing this will help us to be sharp spiritually and ready for whatever God asks us to do, and we will also be ready for any challenges we face in life. Don't be a dull believer, keep yourself sharp through reading the Word, spending time with God in prayer, and putting the Word into practice.