jacobs was born in gettysburg, pennsylvania, the son of professor michael and juliana m (eyster) jacobs. his sister julia jacobs harpster became a missionary in india; his brother michael william jacobs became a judge. he graduated from pennsylvania college in 1862 and from the lutheran theological seminary at gettysburg in 1865. between 1870 and 1883, he was professor at pennsylvania college. he was then appointed professor of systematic theology in the lutheran theological seminary in mount airy, where he also assumed the office of dean in 1894. in 1920, he became president of the seminary when the office of dean was abolished.