Well, there was three different ways Christianity came to African Americans.
1.) Slaves were brought over to America and learned of it there.
2.) In Africa, missionaries shared Christianity and then native Africans came to America.
3.) In Northern Africa, there were Christians that came from the Middle East (some were out of the Diaspora when Rome finally pushed the Jewish people out of their land) and then Africans who were Christians moved to America.
The term African-American isn't limited to slaves that came from Africa, it refers to any African who has been/is an American.
But, if you are specifically asking about previous slaves and how Christianity affected them, then it's a little different.
A lot of slaves accepted Christian beliefs but not all did. I wasn't a slave back then and no one else alive today was either so the best thing to do is read accounts of those who were.
The first is a quote from Phyllis Wheatley, said in her poem "On Being Brought from Africa to America":
'Twas mercy brought me from my Pagan land,
Taught my benighted soul to understand
That there's a God, that there's a Saviour too.. "
What will also help you is to read narratives and accounts of others. There are many (yet not all) who reflect the same feelings as Phyllis Wheatley.
As for influence today, Christianity is still a strong belief among African Americans.
The result is that millions of Africans convert to Christianity every year.
People comverted to the new religions and developed rich traditions and communities
That African Americans needed to create their own communities.
I think a better question would be what is the implications of Christianity on African traditions.
Christianity greatly increaed on the African continent
Some of the immediate effects of American reconstruction were the end of slavery, a change of government in the South to disallow Confederate politicians, and the drop of the southern economy because of the lack of slave labor. Longer-term effects included African-Americans gaining the right to vote, long-lasting racial tensions, and the growth of communities that had mostly or all African-Americans.
they used african methods of farming
Christianity promised freedom
Christianity promised freedom
The traditional African religion influenced most African art, but Christianity influenced Ethiopian art.
African communities relied heavily on religious and family traditions to maintain a stable social structure.
The backcountry is where they can develop small communities