After World War II ended in 1945, the United States entered a period of economic growth, and automobile ownership expanded rapidly. To support this shift, gas stations and service centers became common, and in 1956, the federal government authorized the Interstate Highway System, linking major cities and significantly reducing travel times. In response, property developers began mass-producing suburban housing several miles outside downtown urban centers. Many of Atlanta’s surrounding communities — such as Morrow, Fayetteville, and Forest Park — grew out of this period of suburban expansion. Hapeville was among these developing areas.

During the same era, Catholics in Georgia often faced discrimination from members of other Christian denominations. To ensure access to Catholic education, the Diocese of Savannah-Atlanta began establishing schools for Catholic families. In 1952, diocesan representatives visited Hapeville, then a rapidly growing city, and found that about one hundred Catholic families expressed interest in a parochial school. Construction began in 1953, and on September 19, 1954, the school was formally dedicated. Named for the apostle John, the school opened with approximately 100–120 students in grades one through seven and was staffed by the Sisters of Mercy. Interestingly, its original colors were red and white, and its abbreviated name was "SJS" for "St. John School" rather than the "SJE" today.

In the 1940s, most buildings were decorative and ornate. The following decade, however, saw the rise of modernist architecture — a “less is more” aesthetic that emphasized clean lines and sharp angles. The diocese likely chose this style for the school to draw attention and project authority. The sweeping window walls would have created significant curb appeal, giving the school — and with it, Catholic education — an air of prestige and distinction. In fact, St. John the Evangelist was frequently mistaken for a futuristic commercial factory rather than a school. However, this type of architecture was expensive, and after the 1950s, the diocese returned to traditional brick walls with punched windows.

In 1956, the Diocese of Savannah–Atlanta was divided into the dioceses of Atlanta and Savannah, with St. John the Evangelist placed under the newly formed Diocese of Atlanta. By this time, the diocese was actively working to expand Catholic education throughout the metropolitan area. Its goal was to establish a comprehensive network of Catholic schools that would attract and retain students from early childhood through high school graduation.

In 1957, St. John the Evangelist expanded its academic offerings by adding an eighth grade program, though Pre-K and Kindergarten would not be introduced until decades later. A year later, in 1958, the diocese established St. Pius X Catholic High School. With its establishment, the diocesan vision was realized: a complete feeder system composed of parish preschools, multiple primary schools, and a central diocesan high school serving the greater Atlanta Catholic community.

Although it was considered state-of-the-art at the time, the school originally lacked a library, laboratory, gymnasium, and structured fine arts programs. The building included large amounts of glass but no air conditioning system, and during the warmer months, the classrooms often became unbearably hot. Even the Sisters of Mercy, known for their strict discipline, would often allow students to sleep in class when classrooms got too hot.

Despite these limitations, St. John the Evangelist held a notable distinction: it was the first diocesan school to open with its own football field. Photographs from this period show football and cheer teams wearing bright red and white uniforms, styled similarly to those of modern high school programs.

Two years after the school's establishment, the federal government began acquiring land for what would become Interstate 75, completed through the area in 1957. The school was likely required to sacrifice part of its property for the highway's construction. To ensure student safety and to prevent students from walking to the highway, the school needed to establish a buffer zone between the campus and the new highway.

As the interstate continued to expand over the years, additional portions of the campus property were taken. Eventually, the school no longer had enough space to maintain a full-size football field, and it was reduced in size and repurposed, while the buffer zone evolved into what is now the Marian shrine. The remaining open space was allocated for playgrounds and a convent.