"Gospel" means good news.
We will avoid, for now, the concept of "God the Father – Jesus the Son" which you may find difficult if your experience of a father was unhappy or non existent.
God came to live in a human body on this earth and reveal his solution to our problems. While in Human form he was called Jesus (in English) In his native language he was called Yeshua, which means, "God saves".
When he started his teaching and healing ministry he announced his "Mission Statement" by reading the words of the prophet Isaiah (chapter 61.)
The Spirit of the Sovereign LORD is on me, because the LORD has anointed me to preach good news to the poor.
He has sent me to bind up the brokenhearted,
to proclaim freedom for the captives and release from darkness for the prisoners,
to proclaim the year of the LORD's favor and the day of vengeance of our God,
to comfort all who mourn, and provide for those who grieve in Zion--
to bestow on them a crown of beauty instead of ashes, the oil of gladness instead of mourning,
and a garment of praise instead of a spirit of despair.
The God who created the universe is perfect and good. Therefore he will not compromise and accept bad people or bad things into his presence (Heaven). Obviously we would just spoil it like we spoil our own lives. But what he did was to declare that a punishment had to be carried out for mankind’s wrongdoing and rebellion against His standard. In the holy books of the Jews, which is called the Old Testament by Christians, God set out instructions for behaviour, and punishments for not following these instructions. The death of an animal was acceptable in place of the death of a person who disobeyed and there was a system of animal sacrifice to enable people to be forgiven and live in touch with God.
When God came in the person of Jesus he broke none of these laws. During his life here he developed the teaching in the holy books and went around healing people and renewing their lives, only asking that they put their trust in him. He fulfilled all the requirements of the law in his life.
His time of teaching and healing lasted just three years during which time he established his group of followers to carry on the work. Then he died at the hands of the jealous religious leaders and the cruel civil authorities. But his death was not an unfortunate accident. His death followed the pattern of the lamb that was killed at Passover, to allow God's people to escape from slavery. His death also filled the same purpose as that of the animals killed as offerings to remove guilt for wrongdoing and rebellion against God (the only difference was that Jesus' death was sufficient once for everybody and every wrong deed). Thus His death releases us from slavery to our nature that makes us do wrong and it takes away our guilt before God. The blood that he shed (blood is life in God’s view) is able to deal with all our problems.
He died by being crucified, the cruelest and most degrading death man could devise, but this death fulfilled all the requirements of the law. See The Cross
After three days Jesus rose to life, proving that his death had been accepted as payment for our sin and that we too may rise again after death. His rising again also proved that his blood is powerful enough to heal us and to get us forgiven.