Even though I know it is dangerous to try and compare the importance of the things of God, I would still say that there is one revelation that is more important than anything else. That revelation is the fact that God is a Father God. Lack of this revelation in one way or another is causing more people to struggle in their faith than anything else.
You see, we tend to see Jesus as the Son of God, which He is of course. But then we draw the ignorant or fear-based conclusion that the relationship between Jesus and the Father is somehow different to our relationship with the Father. Let me tell you something: it isn't. If you are in Christ Jesus and are born-again by His Spirit, you have the same relationship to God the Father that Jesus had. This is what grace is all about: He, Jesus, became like us and all that we were without God (separated from God, without hope, according to Ephesians 2) so that we could come into the same form of relationship that Jesus had with the Father while he walked here on this earth.
In fact, the Bible shows this very clearly, so it is strange that we tend to miss it so often. 2 Corinthians 5:21 is a foundation scripture when talking about what Jesus did in the redemptive work: "For He [God the Father] hath made Him [God the Son, Jesus] to be sin for us, who knew no sin [still referring to God the Son]; that we might be made the righteousness of God in Him [God the Son]". Jesus took our sin nature and gave us his righteous nature in exchange. What a glorious trade this is for us, and what a great price our Savior paid for our sake! He truly loves us very much.
When we came to saving faith in Jesus sacrifice for us, the Bible says that we received a new Spirit. This Spirit is described as the Spirit of adoption in Romans 8:15. By this Spirit we cry "Abba! Father!". This word, "abba" is an aramaic word that means literally "daddy". It is the cry of a newly born child who has just learnt to say the word for his father, and it is a word that expresses a very close, personal relationship. We, who were once far away has come nigh unto God through Jesus Christ, our Lord. Hallelujah!
This is what it means that God is our Father. We are His children, joint-heirs of all the Creation together with Jesus. Our Father God loves us and cares for us much more than we could ever care for Him, or even ourselves. All He says and does is founded on this caretaking provision and love. When we grow more aware of this phenomenal fact, we get more secure and righteousness-aware in our relationship with God. We know, that whatever happens, there is nothing that could ever change the fact that He loves us. In fact, He loves us much more than His own life.
All unsecurity and failure to receive from God is caused of doubting this very fact, that God is our loving Father and that He is not holding anything back from us. If we seem to struggle when we need something from God, this is often caused by us not "believing the love" (1 Joh 4:16). Sometimes we simply can't understand that God really loves us as much as He promises in His word. But trust me, whether we understand it or not, He really does. He wants you to come out from a wilderness wandering and go straight into Canaan land — the place where you live and see all the promises of his Word come to pass in your life.
You don't have to stay in the wilderness for 40 years. All it takes is starting to act on the Word of God today, whether you see how it's gonna work out or not. It is not up to you to find out how it's gonna work. That's God's business. Besides, He is much better at worrying about it than we would ever be. Leave it to Him, and trust Him that He will surely do it. Even though you feel like you hardly have any faith at all, Jesus said that all it takes is the size of a mustard seed. That means that you have it, if you are born-again, because Jesus gave it to you along with the new birth. And, you wouldn't have read this far if you didn't believe that this small sermon could help you. So take a good advice and open your Bible right now, find a promise that covers your situation (if you don't have it already), and start thanking God that He will fullfil this promise for you. Keep thanking Him, in faith, until you see it coming. You will be amazed what He will do for you, for no other reason than that He cares for you. He is a Father God.