Our nation was shocked on a spring day in March, when a shooter broke into a Christian school in Nashville, Tennessee, and slaughtered three students and three staff members.

The three students at The Covenant School, run by Covenant Presbyterian Church, were just 9 years old, and the three adults who died included the headmaster, a custodian and a substitute teacher. One of the students was the daughter of the church’s pastor.

Thanks to the heroic actions of officers from the Metro Nashville Police Department, further bloodshed was avoided. They responded within 13 minutes, swept through classrooms and ran toward the gunshots they heard from the second floor. In just two more minutes, those officers took down the killer.

They were true heroes.

Almost immediately, the clamor began in the national media for stricter gun controls. I have my own opinions on that, but my concern goes much, much deeper.

Sadly, the Nashville shooter was a former student at the Christian school, who identified as a transgender man—that is, a female who is seeking to be a male. As I have said before, there is no such thing as a transgender person, only those who are deceived by the sexual culture of our day, which tells a person they can try and live as the opposite sex from what God created them to be. Police Chief John Drake said the shooter was under the care of a doctor for an “emotional disorder” perhaps related to the well-documented issues associated with “gender dysphoria.”

But it is evil in the heart of all men and women that lies at the bottom of what happened that terrible day and what is plaguing our country. The Bible says, “the heart is deceitful above all things, and desperately wicked” (Jeremiah 17:9). We keep searching for solutions to violence and innumerable moral and cultural problems, but at the root of such dark behavior is a heart controlled by sin and evil.

Though our so-called enlightened society would like to deny it, the evil intentions of a sinful heart and soul are responsible for wicked behavior. “From their callous hearts comes iniquity” (Psalm 73:7). Since the fall of mankind in the garden, sin has plagued the human race, every person of every generation. We are born separated and alienated from a holy God who hates every form of evil. We are sinners who have fallen far short of the glory of God.

Thank God for the Good News of Jesus Christ that can transform our hearts through the new birth! Jesus can take the worst of sinners—as the Apostle Paul described himself—and totally change that person from the inside out, through repentance and faith in the saving work of Christ on the cross. In Him, we become new creatures with new natures and with new desires to please the Savior. God powerfully rescues us from the grip of the evil one. The transformation of a sinful heart is only possible through the redemptive work of Christ!“It will take the supernatural power of godly prayer if we hope to turn the tide of wickedness.”

And while some in the media instantly began to mock prayer as a useless tool against evil, I believe we should turn all the more to prevailing, persistent prayer for America. We are dealing with supernatural forces, and it will take the supernatural power of godly prayer if we hope to turn the tide of wickedness. “For we do not wrestle against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this age, against spiritual hosts of wickedness in the heavenly places” (Ephesians 6:12).

That’s why I was so encouraged that on May 4, the National Day of Prayer, Christians across America called on Almighty God for help. The Bible tells us that when times are evil, prayer still works. “If My people who are called by My name will humble themselves, and pray and seek My face, and turn from their wicked ways, then I will hear from heaven, and will forgive their sin and heal their land” (2 Chronicles 7:14).

When believers gather to seek God’s mercy and help, God hears and answers according to His wisdom and will. The National Day of Prayer was authorized by President Harry S. Truman in 1952, three months before I was born. My father was honorary chairman in 2001, and my sister Anne, my son Will, and I have also had the privilege of leading the annual event.

Prayer is powerful because God sovereignly rules over people, nations and empires. As Charles Spurgeon once said, “Prayer is the slender nerve that moves the muscle of omnipotence.”

So, until God calls us to Himself, let us be men and women of prevailing prayer, for ourselves, our families, our cities and towns, and our country. Who knows when God in His mercy and grace will hear our petitions and heal our land.

Believers who have trusted Christ as their Savior also can be assured that evil—no matter how tragic and terrible—never has the last word. Christ triumphed over sin, death and the devil through His death, burial and resurrection. Romans 8:28 stands firm: “And we know that all things [including evil] work together for good to those who love God, to those who are called according to His purpose.”

Remember Joseph, who was sold into slavery by his brothers, falsely accused by Potiphar’s wife and imprisoned for almost 13 years. After God raised him to second-in-command in all of Egypt by His providential hand, he exclaimed to his brothers: “But as for you, you meant evil against me; but God meant it for good” (Genesis 50:20).

God’s coming Kingdom was inaugurated at Calvary, and will one day be consummated when our Lord returns. And make no mistake, when Christ does come again, it will be to totally eradicate all evil and rebellion against Him: “taking vengeance on those who do not know God, and on those who do not obey the Gospel of our Lord Jesus Christ” (2 Thessalonians 1:8).

There will be a New Heaven and a New Earth, where no trace of evil remains and where righteousness dwells forever. What a day that will be!