Christianity and Islam
If you want to understand the heart of a religion, of in the case of Islam, a political-religious system, you must look at its founder, what he taught and how he lived.
Jesus was a man who gave himself completely for the good of others. He taught his followers to love and care for others, even their enemies. He loved and cared for the poor and marginalised. Although there have been aberrations, like the crusades and the inquisition, by and large his followers have done the same. Hospitals, charities, schools, and many other initiatives. Equality under law, abolition of slavery,... I could go on.
Muhammad was a man who among other things married a six year old and consummated the marriage when she was nine. Once he had moved from Mecca to Medina he became a brutal warrior who betrayed people, beheaded hundreds of defeated enemies, took their women as slaves and imposed brutal conditions on conquered enemies. Many of his followers do the same or similar things.
Consider Jesus, and consider Muhammad. There you will see the difference between true Christianity and true Islam.