I know exactly what it feels like.
You can be so joyfully in love with Christ, His Word, His church and everything that entails the Christian faith. But why is this faith not sustained? Even when you are in the midst of your Christian community, you can slowly but surely lose your faith. It has even happened to me. The truth is that nobody is an expert. Only God in His infinite wisdom and mercy truly understands our lives and their swings. Let's take a look at the reasons your faith has been dwindling and some proposed "solutions" for each of them.
1. (Most Common) You were hurt by your community
Somehow, somewhere along your journey toward becoming a mature Christian, you found out that your brothers and sisters are flawed. Some of them are very deeply flawed and can often behave far from the way Christ would behave. When you were hurt by this person or community, you were deeply disappointed in the faith. It happened to me. This, however, is part of maturity. This prompts us to stop looking for people to fulfill the needs that only Christ can fill. This is also a test of love. Can we forgive and love someone who hurt us? This is the solution: Forgiveness. After taking the step to forgive, we must throw ourselves in the arms of Christ. He is our Comforter who loves us ruthlessly and teaches us to love like Him.
2. You have gone through a roller coaster of misfortunes
You lost your job, a family member or a relationship. This is where you begin to ask: "Why, God?" But this is the wrong question to ask. The Word of God says that all things work together for the good of those who love Him (Romans 8:28). It also says that in the world we would have many tribulations (John 16:33). If we are asking this of God, we are living our faith with the wrong expectations. Christ never promised the Christian life to be easy. In fact, He guaranteed it would be very very hard. No matter how hard, He promised He would never leave us nor forsake us (Deuteronomy 31:6). So what is the solution for this one? Trust in the promises of God. Our tears and cares are not going to waste. We need to lift up Psalms and Lamentations up to Him. He is the only One who can change our perspectives and turn our mourning into dancing.
3. You're just busy
Listen, I understand this one, too. At some point in our lives, we needed God to come through for us, and He did. He gave us a job, a family, a career and wonderful relationships. The Word says there is not even a little thing that we can have if it's not given to us from above (John 3:27). But at some point we become so engrossed in the many blessings we asked Him for that we forget about the Giver of the blessings. What we also fail to understand is that He is also the only One who can teach us how to care for those blessings. You cannot keep that job, relationship, career or family on your own strength. You do not know how to. You need an intervention from heaven. The solution is to turn your eyes from the gifts unto the Giver of gifts. You will soon find you enjoy them best this way. You also cease to be anxious because you don't have to work so hard at keeping these things God gave you. You can just enjoy the Kingdom of heaven and its added things with a peace that surpasses understanding.
4. You have apathy
For some reason, you no longer feel joy while attending church, reading His Word or worshiping. You simply do not feel anything. What you do instead is that you start watching TV shows that are not good for you. You also start talking to people and going places that are not good for you. But the only reason you do this is because these things give you more excitement than your Christian life. Your Christian life is boring. I will, however, give you some credit here. The way the American gospel is generally presented is very, very boring. But the gospel of the Bible is nothing short of an adventure. This is the gospel that raises people from the dead, that carries signs and wonders and sees hearts completely turned and changed. This is the gospel that can make a inmate into a king. It changes our credentials from the inside out with power and force. This is a powerful and exciting gospel. I am sorry on behalf of all the Christian leaders who never showed you. However, the solution for this and all the others listed above is right underneath...
Spend. Time. With. God.
Wow. So simple; cliché even. But truly, the heart of your faith is relationship. You focus on the disappointment of your community because your don't focus on God. You focus on your misfortunes because you don't focus on God. You're busy with your ordinary living because you're not occupied with the things of the Kingdom of God. You feel apathy because you forgot your First love. You forgot your First love because you don't have arelationship.
You need God.
Not a little bit of Him. Not a five minute or 10 minute prayer. You need a lot of Him. You need Him all the time. If it were not so, your Bible wouldn't say to pray without ceasing (1 Thessalonians 5:17). It wouldn't talk about abiding in Him (John 15:4). It wouldn't say that without Him we can do nothing (John 15:5). He wouldn't have sent us the Holy Spirit commune with us. We need Him and we need Him deeply. Until we get to the place where you recognize that, we cannot have our faith renewed. With everything going on in the world, I truly believe that the true Christians will be manifested now. Not the ones that are just content with church or mission, but the ones who actually want Him.
Who are you? Do you want Him? Are you willing to do anything to go and get Him? He has been pursuing His Beloved patiently. He has been pursuing you.