It was over 300 years after Christ. Constantine, began to embrace the belief of Christianity, because he saw it as a way to bring about Christians to fight in the name of faith for his cause against Muslims. So he told them he saw a sight, a cross and God's voice who told him by this sign you shell conquer. And goes the legend of the crucifix. etc... and the other traditions began by what be the new founded Catholic church. Constantine used them, and then so did the those who would lead the church.
You have to also be aware that Christianity also spread else where before the catholic church was formed. Other churches (places of gathering not denominations) where build before the catholic church , although most didn't survive as long. Partly do also because of Constantine first saw them as a threat, although later used them to his advantage against the Muslims.
Second reason the Catholic church after being formed made alliance with the kingdoms in exchange for protection. The catholics church blessed their kingdoms, and gave kings the appearance of legitimacy with God. Just as King David, was blessed by God. Taking advantage of the gullibility and ignorance of early men. It seems men hasn't change much their either. The church then began target all other churches and individuals, who did not give up their sovereignty to the catholic church and prosecuted them as with charges of being heretic, satanist etc... in order for the Catholic church to maintain a monopoly. Along with the support of allied kingdoms and the catholic church own military. the catholic church was unstable.
Jesus left no church, only the covenant of men with God. That is all he left.