He studied at the Pelplin Higher Seminary ( Wyższe Seminarium Duchowne w Pelplinie) and was ordained a Roman Catholic priest in Chelmno (Culma, Kulm) in 1963.

While serving as Bishop he received Commander's Cross of the Order of Polish Rebirth.

[3] He was named an honorary citizen of Chojnice (1994), Starogard Gdański (2007) and Gdynia (2008),[4] and received the 2010 Award For Services to Pomerania.

[5] Szlaga's health declined just before he was to act as main consecrator of the new Auxiliary Bishop Wiesław Śmigiel and he died on April 25, 2012.

He is buried beside the altar at the Cathedral Basilica of the Assumption of the Blessed Virgin Mary at Pelplin Abbey.