How are they to believe in Him of whom they have never heard?

Romans 10:15 is very clear..how can they believe in Him of whom they have never heard? Jesus Christ has commanded christians to preach the gospel to every creature because all mankind is guilty and stands condemned in His sight. The brutal death and triumphant resurrection of Jesus Christ has made it possible for man to be justified. Jesus is the one who sets a man free from ultimate penalty of sin...eternal damnation. But we must come to Him believing that He was crucified and is Risen..that He is Lord..and our Lord. How can I as a christian..having Jesus Christ within me ever not preach the gospel? woe is me if i preach not the gospel! For i know my Savior and why He came...to seek and save the lost..to bleed..to deny Himself! So to must i deny my life and lay it down for His name sake and the gospels! People are perishing and we must warn them and plead with them to come to Jesus Christ!