I would really appreciate it if someone could tell me how slavery affected religion in the south? Not how religion was at the time of slavery in...

The most direct effect of slavery on religion you've already mentioned: Most slaves taken from Africa were forced to convert to Christianity.

But there were other, more complex effects that slavery and its surrounding culture and institutions influenced the development of religion in the South; the Baptist and Methodist denominations we know now largely grew out of that milieu.

Many African-Americans preserved traditions from the African religions they were forced to leave behind, which is another reason why singing and dancing are such an important part of many Baptist religious ceremonies today. European Christianity generally frowned upon dancing and singing, but in the most difficult of circumstances people fought to preserve what they could of the culture they left behind thousands of miles away.

Perhaps in response to the extreme inequality exemplified by slavery, a new vein of Christian religion formed in the mid 18th century during what was called the Great Awakening (and then the Second Great Awakening); where previously religion had been focused upon hierarchy and ritual (similar to Catholic and Orthodox churches today), this new approach focused upon personal belief, salvation, and equality in the eyes of God.

The effect of this new egalitarian religion upon slaves was somewhat mixed; while some used it to argue for ending slavery, for others it actually seemed to placate them, making them more willing to accept their current plight in the hopes of a reward in Heaven. Perhaps because of this, slaveowners were also mixed in their willingness to allow their slaves to learn about religion; some actively resisted it, fearing the slaves might try to revolt, while others considered it their holy duty to spread Christianity to their slaves.

Many of the churches that were formed during this period carried on for centuries afterward, and formed the origins of modern churches today. We can still see many differences between the practices of predominantly White churches in the North and predominantly African-American churches in the South that ultimately derive from this period and the integration of African traditions with Christian beliefs.