Republic of Ireland is called a 'saint's country' since more than 90% of population believe in Catholicism. The Irish Catholicism had a great influence on the Irish society and culture by offering the hierarchical order to Irish people's way of life. And also, Catholicism had been a symbol of nationalism and played the role to confirm a sense of national identity. It is also true that since Free State Ireland, Catholicism with the word 'Gaelic' has contributed to making the national identity or 'racy Irish atmosphere'. However, the Irish Church of the 20th century was dedicated neither to spirituality nor the intellectual enhancement of the faith, but to material and social advantage. At the first stage of his writing, Yeats tries to consider Irish Catholicism as holy, combining it with mysticism of theosophy. And also he uses it to strengthen nationalism. However, Catholicism of that time, unlike what Yeats thought, sticks to the practical line, which makes Yeats criticize its materialistic ends. Meanwhile, talking about Heaney, although he accepts its values of contributing to the communal union and he himself is a serious devotee to pilgrimage going to Lough Derg or Station Ireland. Heaney feels at ease because of Catholic's fanaticism and oppression imposed on individuals. The final conclusion of this paper is that although these two poets, Yeats and Heaney, accept that Irish Catholicism has contributed to inspiration of the national patriotism and promoted the modernization of independent Ireland, they criticizes that Irish Catholicism is lacking its artistic spirituality and that it is a trap from which artists are to escape.