If you can’t explain it simply, you don’t understand it well enough. ~Albert Einstein
The gospel is simple enough for a child to understand, and if you do not understand that, then you have yet to understand the gospel.
And I, brethren, when I came to you, came not with excellency of speech or of wisdom, declaring unto you the testimony of God. (1 Corinthians 2:1)
9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. 10 For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. 11 For the scripture saith, Whosoever believeth on him shall not be ashamed. 12 For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him. 13 For whosoever shall call upon the name of the Lord shall be saved. (Romans 10:9-13)
(All scripture references from the KJV.)