He participated in street demonstrations, distributed leaflets, and photographed anti-communist posters and slogans for documentation purposes.

[1] In February 1984, Siciński first encountered the Seventh-day Adventist Church congregation in Łódź, where he listened to lectures by Władysław Polok [pl].

[8] Andrzej Siciński participated in the ecumenical translation of the New Testament, serving as a consultant for the Seventh-day Adventist Church.

[9] Siciński is also a signatory of the Declaration by the Council of the Polish Episcopal Conference for Ecumenism and the Leadership of the Seventh-day Adventist Church in Poland, marking the 15th anniversary of interdenominational dialogue.

It also facilitated the opening of cultural centers in small towns that had previously refused to rent their spaces to Adventists.

[11] Siciński emphasizes the importance of finding common ground for peace and fostering a proper atmosphere in interactions with people holding different views.

Siciński assessed that those conducting the lustration were closer to Old Testament ethics than to Christ's command to love one's enemies.

[15] He also criticized President Komorowski's minister, Prof. Krzysztof Szczerski, for his proposal to turn Poland into a confessional republic.

[17] He criticized Jarosław Kaczyński for his statement that outside of the church there is only nihilism, for identifying Polishness exclusively with Catholicism, and treating non-Catholics as second-class citizens.