The Book of Luke is addressed to Theophilus.
The third of the Gospels is that of Luke. Luke was a companion of Saint Paul and he also wrote the Book of Acts. Both books are addressed to a man named Theophilus. We do not know who Theophilus was; the name means "lover of God" so it may be a title rather than a name. Theophilus may also have been a Roman official as he is referred to as "most excellent", a term used elsewhere to describe Roman officials.
Luke was a Greek from the city of Antioch in Syria, and he is the only Gentile author found in the New Testament. His Gospel is intended to strengthen the faith of Gentile Christians; especially Greeks. He also wants unbelieving Greeks to hear about Jesus and come to believe in Him.
Luke 10:29-37
"But he, willing to justify himself, said unto Jesus, And who is my neighbour? And Jesus answering said, A certain man went down from Jerusalem to Jericho, and fell among thieves, which stripped him of his raiment, and wounded him, and departed, leaving him half dead. And by chance there came down a certain priest that way: and when he saw him, he passed by on the other side. And likewise a Levite, when he was at the place, came and looked on him, and passed by on the other side. But a certain Samaritan, as he journeyed, came where he was: and when he saw him, he had compassion on him, and went to him, and bound up his wounds, pouring in oil and wine, and set him on his own beast, and brought him to an inn, and took care of him. And on the morrow when he departed, he took out two pence, and gave them to the host, and said unto him, Take care of him; and whatsoever thou spendest more, when I come again, I will repay thee. Which now of these three, thinkest thou, was neighbour unto him that fell among the thieves? And he said, He that shewed mercy on him. Then said Jesus unto him, Go, and do thou likewise"