It's a struggle he's had both as a layman and as a pastor, of one of the fastest growing and largest churches in the country. And it's a struggle he wants to help millions of so-called Christians to overcome.
Christian atheists are everywhere, Groeschel, who leads LifeChurch.tv, writes in his newly released book, The Christian Atheist.
They attend church and seminaries and some even read their Bibles everyday.
"Many of us look the part," the Edmond, Oklahoma, pastor says. "Or we think we're Christian because, you know, it's not like we're Buddhists. We believe in God, but our lives don't reflect who he really is."
Groeschel introduced Christian atheism a few years ago in a sermon series titled Practical Atheist.
The way Christian atheism plays out, he preached at that time, is: "I believe in God but I want to do whatever the heck I want to do. I want enough of God to keep me out of hell and enough of God to get me into heaven but I don't want so much of God that it makes me change my lifestyle because at its root I believe in God but I do not fear Him."
The four-week series proved to really connect with long-time churchgoers and more than 2,100 people ended up giving their lives to Christ.
Groeschel is hoping that that more people in the pews, the Easter and Christmas Christians, the cultural Christians, and those who simply believe in God but live an atheist lifestyle can shed their hypocrisy and see that there is a better way to live.
Cultural Christian
Like many, Groeschel was born into a "Christian" family. They would go to church when convenient, donate goods to food drives and pray before meals. But that was the extent of it, he says.
He knew about God and believed in God but he didn't know God.
Even the demons believe in God, he notes. So, obviously there is more to the whole Christian thing than just believing in God, he says.
It wasn't until college when he read the New Testament books of Romans and Ephesians and discovered salvation was by God's grace alone that he transformed from a Christian atheist into a Christian.
"For the first time in my life, I believed in God and began to live like he is real," Groeschel writes.
As a transformed believer, he became more than a fanatic and began "collecting converts to Christianity like Michael Phelps collects gold medals". He went into ministry at the age of 23 and though his love for ministry burned hotter, his passion for Christ cooled.
"My mission had become a job," he recalls.
Again, he began falling into Christian atheism and by the age of 25, he was a "full-time pastor and a part-time follower of Christ".
Believing in God but ...
Some of the symptoms of Christian atheism are illustrated in his past life but there are also symptoms that may be difficult to recognise, especially by those who are infected, Groeschel points out.
Believing in God but pursuing happiness at any cost is one of them.
To the Christian atheist, the pursuit of happiness gives license to sin. And happiness to them is based on the things in this world rather than God's kingdom.
Moreover, "to the Christian atheist, the holy God of the universe is quietly transformed into a cosmic soda machine. If we give enough money, or pray the right prayer, or live the right way, God must deliver and do what we ask."
Pursuing happiness seems like the right thing to do, but Groeschel stresses, "God doesn't want us to be happy."
"God doesn't want us to be happy because God wants us to be blessed," he explains.
"When we believe the things of this world will provide happiness, we're settling for a counterfeit," he says. "The happiness of this world is based on fickle happenings, but the blessings of God transcend the things this world offers."
Other symptoms include believing in God but not being certain that He loves you, not really knowing Him, not believing in prayer, not thinking He's fair, not thinking you can change, trusting more in money, worrying all the time, shunning the church, and not sharing your faith.
"I believe one of the main reasons people don't share their faith in Christ is that they don't really believe in hell," Groeschel offers. "Many of us are out of touch with the genuine urgency."
"If we really believed in heaven and hell – and we sincerely cared – wouldn't our actions be transformed?"
Crossing the Third Line
Several years ago in ministry, Groeschel went through another transformation.
He had increasingly recognised inconsistencies between what he claimed to believe and the way he actually lived. Though he preached that people without Christ go to hell, his life showed he wasn't equally passionate to reach those people. Though he preached that prayer is critical, his prayer life was virtually nonexistent. And he surrendered parts of himself to Christ rather than his whole life.
One day he cried out for God and was born again – again. He crossed over the "third line", as he describes it.
Most people are line-one and line-two believers – they believe in God and the Gospel of Christ enough to benefit from it (but not change their lives) or they believe enough to contribute comfortably (give back as long as it doesn't cost too much).
But Groeschel calls Christians to cross the third line – believe in God and Christ's Gospel enough to give your life to it. Anything less, he says, doesn't seem like real Christianity to him.
Though it took him almost two years to cross the third line, he says he is now a different person, one who desires nothing more than all of God.
"Step across the line," he encourages Christians. "Welcome to true Christianity."