Christianity vs. Islam

I have heard a few days ago that Islamic believe in Adam and Eve.

"According to Qur'an, Allah created Adam, the first human, out of dust and commanded the angels to bow to Adam. Satan, also present, refuses due to his pride, and is banished from the heavens."

If the Christianity and Islam had had the same roofs, why was their ways later separated?

there are so many things in Christianity and Islam that are similar. But at the same time there' are so many things that are against each other.
For example in Islam we believe that Jesus Christ was not killed on the cross. Christians believe that Jesus Christ was killed on the cross and that he was the son of God.

we believe that he was taken to the heaven alive and that he will come back, not as a prophet, but as a Muslim who is following prophet Muhammad peace be upon him.

i think the some part are similar to them but jesus are created by god i think the christian is believing on jesus and islamic people believed in god that s the main difference

I Think their teachings are different so they are merely separated. Although they have the same roots, they value still having a deeper faith among god or allah and doing goodness to others and themselves.

There are a lot of thing which are similar between religions that's why there is a discussion around the whole countries to work together and discuss the common things of religions and promote them to common people so that our planet can be peaceful.