Many people are drawn to a religion because of a certain preacher or group of preachers. If the preacher is charismatic, a powerful speakers, humorous, etc. then people often flock to hear such men.
The Bible emphasizes the importance of preaching (2 Tim. 4:2; 2 Tim. 2:2; Acts 20:20; Acts 20:27) but also points out the duty of those who hear (Luke 8:18; Mk. 4:24). In the Parable of the Sower in Mt. 13:1-9, Jesus emphasized the responsibility of the hearer as he described the heart of men as soil which receives the seed which is the word of God (Luke 8:11). Jesus wants all men everywhere to have “good soil” hearts which receives, believes and obeys His word and brings forth fruit to God.
Steve Hudgins has an old chart sermon entitled, FRUITFUL HEARERS, which makes for a good study on how those who hear and obey God must bear fruit.