Luke was a physician (Col 4:14). Physicians usually have greater powers of observation than most other people. This enables them to make better diagnoses. Traditionally, Luke also has been known as an artist. Artists likewise have greater powers of observation.
Luke accompanied Paul in his missionary work (see 2 Tm 4:11). For many years, Luke saw firsthand the wondrous works of the Holy Spirit in the Church's first generation.
Luke probably completed the final editing of his Gospel and the Acts of the Apostles around 85 A.D. Thus, Luke had the opportunity to witness much of the first fifty years of the Church.
Luke left his profession of being a doctor so he could give his life to the Lord as an evangelist and a missionary.
Luke's natural talents, training, missionary experience, and years of total commitment to Jesus gave Luke exceptional, penetrating insights into God's plan of salvation. He saw the centrality of the Holy Spirit in the Christian life (e.g. Lk 4:18; 11:13; Acts 1:8; 2:4). He recognized forgiveness (e.g. Lk 15:11ff) and prayer (e.g. Lk 18:1; Acts 1:14; 2:42) as keys to life in the Church. Luke saw how important in God's plan are the poor, the Samaritans, and women. Most importantly, Luke saw clearly that Christ's disciples are to be missionaries who live and die to proclaim the Gospel to all nations.
Read Luke's Gospel and the Acts of the Apostles. Look into the heart of the Gospel. Come, Holy Spirit!