What are the main similarities and differences between Christianity and Islam?

Christianity and Islam are the two largest Abrahamic, monotheistic faiths and share common historical roots, prophets (like Abraham, Moses, and Jesus), and belief in a judgment day. However, they are fundamentally and irreconcilably different on the central issues of God's nature (Trinity vs. absolute unity), the identity of Jesus Christ (Son of God vs. a human prophet), and the means of salvation (grace through faith vs. submission through works). These differences affect every major doctrine, making the faiths distinct paths.