Billy Sunday, former baseball player

Billy Sunday (1892-1935) was a baseball player who became the most celebrated and influential American evangelist at the beginning of the 20th century.
In either the 1886 or 1887 baseball season, while in Chicago, he went with several of his team mates into town. They listened to a gospel preaching team from the Pacific Garden Mission. He started to attend services and after a struggle decided to become a Christian. After his conversion he changed his behaviour and shortly afterwards began speaking in churches.
In 1893 he became the full-time assistant to John Wibur Chapman, a well known evangelist. When Chapman unexpectedly returned to the pastorate in 1896 Billy struck on his own. For 12 years he preached in 70 communities.
Taking advantage of his reputation as a baseball player he generated advertising for his meetings. He became the nation’s most famous evangelist with his colloquial sermons and frenetic delivery.

Sunday was a supporter of Prohibition and played a significant role in the adoption of the 18th amendment.

Wikipedia main source for this information