A devout Catholic, Ahn at age 19 was deeply pious and focused on everything Catholic as well as learning 

catechism earnestly. Ahn helped Fathers as a Catholic beatus and was active in propagation of Catholicism. 

A lion’s share of the contents in Autobiography of Ahn Eung-chil by Ahn Jung-geun is fully devoted to those related to Catholicism. Ahn explained God’s omnipresence and omnipotence as well as complete goodness and perfect righteousness, saying that God judges the world and dispenses reward and punishment to each soul. Reward is the everlasting blessing of heaven and punishment is the everlasting pain of hell, according to Ahn.

“Men are destined to live no longer than 100 years at the utmost. The wise and the foolish alike and the precious and the underprivileged people alike, men are born naked and die without a shred of clothing, too. ‘Coming empty-handed and leaving the world with an empty pocket’: that is the core message. …… If people don’t believe in heaven and hell under the reason that they haven’t seen heaven and hell, it is as if a posthumous son wouldn’t believe in existence of his father under the reason he hadn’t seen his father and as if a visually handicapped person wouldn’t believe in the existence of the sun in the sky under the reason that he hadn’t seen the sky. …… Almost all men of considerable learning with broad vision around the civilized world believe in Jesus Christ. Jesus told his disciples, “In generations to come, hypocrites will appear without failure and mislead the people using my name. You should not make a blunder. Christ is the only gate to heaven.”

Though Thomas Ahn Jung-geun lived a very short life, he weathered the crisis with a firm belief in Catholicism and Jesus Christ, all for the independence of Korea and the peace of East Asia.