Why were the Orthodox countries, together with the Catholics, unable to resist the Turkish conquest?

The Ottoman state was a strong administrative state formation. A well-trained Turkish army with the ideology of the superiority of Muslim beliefs over Christian ones was a dangerous enemy for Europe. The policy of conquest of all the sultans provided for the expansion of the state. The Ottoman victories were facilitated by the fragmentation of the Western and Eastern Slavs. Having corrected all the accepted provisions of the Union of Florence, Christians weakened their positions in opposition to the Gentiles. The papal throne chose a wait-and-see attitude and did not provide significant assistance to the struggling Christian countries.