He founded the Catholic side line of the Cirksena in the Westphalian County of Rietberg, the so-called house of East Frisia.
Under the Treaty of Berum, Sabina Catherine had been awarded the County of Rietberg, which her mother Walburgis had brought into the Cirksena family.
John had converted to the Roman Catholic faith at an early age, and needed papal dispensation to marry his niece.
That he didn't convert only for political reasons, was made evident when he founded a Franciscan monastery in Rietberg.
After Sabina Catherine died in childbirth giving birth to her eleventh child, in 1618, John ruled Rietberg alone until his death in 1625.