We need a voice - a preacher, a true minister of God - to make the message clear.
By nature, our desires are likely to run amok. We think we know what we want, but we do not always know what we need. A minister's function within the church is to lead us from what we want to what we need.
A brief article excerpted from an old Fortune magazine article chided church pastors for following rather than leading their flocks. The result, it said, was a vicious, downward spiral of spiritual disillusionment in the congregates. The following quotation from that article is quite insightful:
There is only one way out of the spiral. The way out is the sound of a voice. Not our voice, but a voice coming from something not ourselves, in the existence of which we cannot disbelieve. It is the earthly task of the pastors to hear this voice, to cause us to hear it, and to tell us what it says.
This statement is backed up by Romans 10:13-17:
For "whoever shall call upon the name of the LORD shall be saved." How then shall they call on Him in whom they have not believed? And how shall they believe in Him of whom they have not heard? And how shall they hear without a preacher? And how shall they preach unless they are sent? As it is written, "How beautiful are the feet of those who preach the gospel of peace, who bring glad tidings of good things!" But they have not all obeyed the gospel. For Isaiah said, "Lord, who has believed our report?" So then faith comes by hearing, and hearing by the word of God.
How can people call on God if they never heard of Him and do not know Him? Paul answers that they cannot hear without a preacher. A preacher cannot go unless he is sent, commissioned as an ambassador with a message revealed to him. Paul's summary is that faith - saving faith - arises from this combination of acts after the message is heard and believed. Faith comes by hearing the Voice of God spoken through a duly ordained messenger of God. This, in effect, means that only He who sends the message can designate who bears it!
In addition, Paul is not simply describing the beginning of faith, but its beginning and all of the progress made by faith throughout a person's conversion. The very strength of faith is by hearing and believing. Salvation is by grace through faith (Ephesians 2:8). Faith is the key that opens the door of salvation, but only to those who will hear and believe and redirect their lives accordingly.