Sopoćko was born to Polish parents in 1888 in Juszewszczyzna (also known as Nowosady) near Valozhyn within the Russian Empire, now Belarus.

Sopoćko was very supportive of the Divine Mercy devotion of Faustina Kowalska and in her diary (Notebook V, item 1238) she stated: "This priest is a great soul, entirely filled with God."

Sopoćko managed to obtain permission to place the painting within the Gate of Dawn in Vilnius as he celebrated the Mass that Sunday.

[7][8] In the summer of 1936, Sopoćko wrote the first brochure on the Divine Mercy devotion and obtained the imprimatur of Archbishop Jałbrzykowski for it.

[4] In an entry in her diary on 8 February 1935, (Notebook I, item 378), Kowalska had written that the Divine Mercy devotion would be suppressed for some time after her death but then be accepted again although Sopoćko would suffer for it.

[12] In 1965 Karol Wojtyła, then Archbishop of Kraków and later Pope John Paul II, opened a new investigation and submitted documents in 1968, which resulted in the reversal of the ban in 1978.

An estimated 80,000 people attended, including the Polish president, Lech Kaczyński, and the speaker of the Parliament of Poland, Bronislaw Komorowski.