The Gospel is preached because you need a Saviour. You need Jesus! God so loved the world that He gave His only Son, Jesus Christ that you might be saved.
Bible Scriptures: Darby Translation
Isaiah 28:14-18 “14 Therefore hear the word of Jehovah, ye scornful men, that rule this people which is in Jerusalem.15 For ye have said, We have made a covenant with death, and with Sheol have we made an agreement; when the overflowing scourge shall pass through, it shall not come unto us; for we have made lies our refuge, and under falsehood have we hid ourselves.16 Therefore thus saith the Lord Jehovah: Behold, I lay for foundation in Zion a stone, a tried stone, a precious corner-stone, a sure foundation: he that trusteth shall not make haste.
17 And I will appoint judgment for a line, and righteousness for a plummet; and the hail shall sweep away the refuge of lies, and the waters shall overflow the hiding-place.18 And your covenant with death shall be annulled, and your agreement with Sheol shall not stand; when the overflowing scourge shall pass through, ye shall be trodden down by it.”
Luke 6:47-49 “47 Every one that comes to me, and hears my words and does them, I will shew you to whom he is like.48 He is like a man building a house, who dug and went deep, and laid a foundation on the rock; but a great rain coming, the stream broke upon that house, and could not shake it, for it had been founded on the rock.
49 And he that has heard and not done, is like a man who has built a house on the ground without [a] foundation, on which the stream broke, and immediately it fell, and the breach of that house was great.”
1 Corinthians 3:11 “11 For other foundation can no man lay besides that which [is] laid, which is Jesus Christ.”