A taste of an explanation of the importance of Cornelius to the church (from For All the Saints):
The experience of Cornelius’ household was regarded as comparable to a new Pentecost, and it was a primary precedent for the momentous decision of the apostolic council, held in Jerusalem a few years later, to admit Gentiles to full and equal partnership with Jewish converts in the household of faith.
Collect for the Day
O God, by your Spirit you called Cornelius the Centurion to be the first Christian among the Gentiles; Grant to your Church such a ready will to go where you send and to do what you command, that under your guidance it may welcome all who turn to you in love and faith, and proclaim the Gospel to all nations; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, for ever and ever. Amen.