"Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavens" (Ephesians 1:3).

This passage comes from St. Paul's letter to the Ephesians. In the letter, Paul addresses the Gentile believers in Christ and encourages a sense of Christian unity, Rev. Jeremiah Johnston told Fox News Digital.

Johnston is pastor of apologetics at Prestonwood Baptist Church in Dallas. He's also president of the Christian Thinkers Society. 

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A pair of recent experiences – one in the ruins of the city of Ephesus and one at home in Texas – helped make the message of unity in Ephesians seem even more meaningful, he said. 

"A few weeks ago, as I taught university students within the marvelous ancient ruins of the city of Ephesus, my focus was on how St. Paul's powerful opening doxology to the Christians of Ephesus is summarized in two powerful words: 'In Christ,'" Johnston told Fox News Digital in an email.

Johnston was in Ephesus, in what is modern-day Turkey, with college students as part of the Impact 360 Institute, a "nonprofit organization dedicated to equipping young adults with a biblical worldview and leadership skills that will enable them to impact their communities and the world," he said. 

The overarching theme of the opening verses of Ephesians is stressing the need for unity with Christ, Johnston said, and the phrase "in Christ" is found "no less than 11 times." 

During Paul's time, the city of Ephesus had a population of 250,000, Johnston said, and was home to the Temple of Artemis, one of the seven wonders of the ancient world. 

"Paul invested more time ministering in the city of Ephesus than any other place" and spent three years in the city as his "base," Johnston said. 

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While Ephesus was a major city in early Christianity, however, the city had a "detestable side," Johnston said, referring to the slave market. 

"For 200 years (100 BC to 100 AD), Ephesus was the headquarters of the Roman slave trade and, as such, was the largest slave market in the empire," he said. 

"Slaves were valued by their appearance, age, physique, education, skill-set and, yes, the condition of their teeth" — something that would be "horrifying" to anyone in the modern world, Johnston said. 

Paul's time, he said, was one of division. "People were divided by race, by free or slave status and by gender," he said. 

So the message of unity "in Christ" was one that was sorely needed, both by the Christians in Ephesus and by Christians today, he said. 

"But what does it mean to be ‘in Christ’? Believers share in all the pivotal accomplishments of Christ, meaning that what is true of Christ in His resurrection is also true for those who believe in Him," Johnston said. 

A Christian, a follower of Jesus, "shares everything Christ is and everything Christ has," he added.

"The truth we lay hold of in this passage is that when you believe in Christ, you are connected to Him in an unbreakable bond. You are united to Him; indeed, you become one with Christ."

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Paul's message that Christians are united in their identity "in Christ" would not have been accepted by most in the region, Johnston said.

"Many would have thought Paul's ideas laughable, which is why Paul used the identifier of 'in Christ' 73 times throughout his epistles," Johnston said.

But Johnston said, "There is no truth more important, and no truth more forgotten by modern believers, than the identity of the Christian being 'in Christ.'"

"Paul taught the Ephesians that all people were not only made in the image of God, but that they could also be powerfully linked spiritually with Christ by grace through faith," he said. 

Last week, Johnston baptized his triplet sons on their 8th birthday. It was an experience he called "profoundly sacred" and further drove home the importance and significance of what it means to truly be united "in Christ."

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"When contemplating baptism, some of the most important things we wish to express elude even our best words," he said. "This is why powerful symbols – ordinances – exist in the Church."

Baptism "clarifies what the finest human expressions can merely allude to: the profound eternal reality of forgiveness of sins and everlasting life alongside Jesus and the redeemed family of God," Johnston said.

He continued, "The overwhelming truth of the Gospel is that we exist eternally forgiven 'in Christ,' and the baptism of my boys symbolizes the deeper truth that my children will be there with [wife] Audrey and me." 

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"Therefore, as to our new identity, if we have trusted in Christ, we belong to the royal family of God," he said. "My identity is, more than anything else, 'in Christ.'" 

In modern times, when people "rush to escape reality," a reminder of this truth is much needed, Johnston said.

"We need to be radically reminded that our value and identity is based on the unchanging grace and love of God in Christ," he said.

"That is, when we as Christians think about who we are, we are primarily to understand ourselves as being someone who is 'in Christ,'" Johnston said — meaning we are "accepted, forgiven, forever loved and connected to our creator and savior, the Lord Jesus Christ."