The following statement of belief (Nicene Creed) was written in 325 AD and is still, today, as eloquent a summary of what we believe as has ever been written.  (I edited it to counter the more recent counterfeit religions.)

I believe in one ultimate God, the Father, the Almighty Jehovah, 
maker of heaven and earth, of all that is, seen and unseen.  
He has given us his great and precious promises that by them I may participate in the divine nature and  escape sin. 

I believe in one Lord, Jesus the Christ of Nazareth, the only Son of Jehovah,
eternally begotten of the Father, God from God, Light from Light,
true God from true God, begotten, not made, of one Being with the Father.
Through him all things were made.
For me and for my salvation he came down from heaven:
by the power of the Holy Spirit he became incarnate from the Virgin Mary, and was made man.
For my sake he was crucified under Pontius Pilate; he suffered, died and was buried.
On the third day he rose again in accordance with the Scriptures;
He ascended into heaven and is seated at the right hand of the Father in power.
He will come again in glory to judge the living and the dead, and his kingdom will have no end.

I believe in the Holy Spirit, the Lord, the giver of life, who proceeds from Jehovah and Jesus Christ of Nazareth.
With the Father and the Son he is worshiped and glorified, proving he is God.  
He has spoken through the Prophets.  He has attested to the gospel message with signs and wonders.
He has conferred His Authority over demons to me.
I believe in one holy Church, the bride of Christ, made up of those chosen for salvation.
I acknowledge one baptism as a sign of the forgiveness of sins.
I look for the resurrection of the dead, and the life in the world to come. Amen.