An entirely different culture.
Christianity in its true form, is really at heart an entirely different culture—and that's what can make it so hard to actually embrace. Jesus even said that He did not come to bring peace, but a sword, in that,
"I came to set a man against his father, and a daughter against her mother, and a daughter-in-law against her mother-in-law; and a man’s enemies will be the members of his household. He who loves father or mother more than Me is not worthy of Me; and he who loves son or daughter more than Me is not worthy of Me. And he who does not take his cross and follow after Me is not worthy of Me." (Mt 10:36-38)
We have to leave culture behind, including the culture of our families. That's a tough thing to do—almost like boot camp.