Genetic engineering is the modification of an organism's genetic material to alter its traits through adding, deleting, or changing specific genes. CRISPR-Cas9 systems are groundbreaking tools for genetic engineering, in short utilizing a molecule called RNA to guide a protein called Cas9 to a specific location in DNA to add, delete, or replace genes. The history of how the CRISPR-Cas9 systems came into existence, how it was adapted from a natural defense system in bacteria, and its mechanism of action in both are explained. Its applications, both present and future, competing genetic modifiers, advantages and disadvantages, and the ethical dilemmas surrounding genetic engineering as a whole from a Christian perspective are also discussed throughout this review.