Yes. Stalin attended Tiflis Theological Seminary.

Biographical records agree that Stalin attended the Tiflis seminary in the 1890s, although he never completed his studies or became a priest. The reason he left is disputed: the seminary recorded that he did not attend exams, while Soviet-era and later accounts say he was expelled for revolutionary activity. The fact that he attended is not in doubt.

• He first attended the church school in Gori, then won a scholarship to the Tiflis Theological Seminary in 1894.
• He left in 1899; accounts differ on whether he was expelled for missing exams or for Marxist activity, or whether he withdrew.
• At the seminary he joined secret Marxist reading circles.
• He later became a professional revolutionary and Bolshevik, and led the Soviet Union from the mid-1920s until his death in 1953.

Stalin's seminary education is a well-established historical fact. During his time there, he became interested in Marxism and revolutionary politics rather than pursuing the priesthood.

• Stalin entered the Tiflis Theological Seminary in 1894.
• The seminary trained men for the Orthodox priesthood.
• He left in 1899 without graduating and never became a priest.

Joseph Stalin (born Ioseb Jughashvili) was sent to religious school by his mother, Ekaterina Geladze, who wanted him to become an Orthodox priest. In 1894, he earned a scholarship to the Tiflis (Tbilisi) Theological Seminary, the premier center of higher education in Georgia at the time. While studying there, he became disillusioned with the strict religious administration, turned toward revolutionary politics, and embraced Marxism. In May 1899, he was expelled after missing his examinations, after which he became a full-time political agitator.

• Stalin's mother, a devout Georgian Orthodox Christian, enrolled him in church schooling with the intention that he become a priest.
• After attending the Gori church school, he entered the Tiflis Theological Seminary in modern-day Tbilisi in 1894 on a scholarship.
• During his five years there, he secretly read forbidden texts, including Karl Marx, and joined underground Marxist groups.
• He was expelled from the seminary in 1899, officially for failing to attend his final examinations.

This is a well-documented matter of record rather than a contested claim. Stalin's time at the Tiflis Theological Seminary is covered in standard biographies and he was an enrolled student there from 1894 to 1899, so the ordinary reading of the question — did he attend a seminary — is plainly satisfied. The only nuance is why he left, since sources disagree between expulsion and voluntary withdrawal, but that does not affect whether he went.

• Stalin entered the Tiflis Theological Seminary in Tiflis (now Tbilisi), Georgia, in 1894.
• He studied there for about five years, until 1899.
• He left in 1899; accounts differ on whether he was expelled for revolutionary activity, for missing examinations, or for requesting to leave.
• While a student he joined underground Marxist discussion circles and read banned revolutionary literature.
• He did not graduate and never became a priest.

Multiple reliable sources confirm that Joseph Stalin attended the Tiflis Theological Seminary (also known as the Tbilisi Spiritual Seminary) as a young man. He entered the seminary at age 14 in 1894 and remained there until 1899, when he was expelled. The reasons for his expulsion are generally attributed to his failure to take final exams and his involvement in revolutionary activities, though some debate exists about the exact circumstances. The evidence for his attendance is overwhelming and settled in historical scholarship.

• Stalin attended Tiflis Theological Seminary from 1894 to 1899.
• He received a scholarship to attend the seminary.
• The seminary was a Russian Orthodox institution in Tbilisi, Georgia.
• Stalin was expelled in 1899 for missing his final exams and rebellious behavior.
• He studied both secular and theological subjects during his time there.

1. Tbilisi Theological Seminary en.wikipedia.org
2. TIL Joseph Stalin originally trained as a priest in an Orthodox Spiritual Seminary. He at first achieved high grades, but later lost interest, declaring himself an atheist. He was known to stalk out of prayers, refuse to doff his hat to monks, and was confined to a cell for his rebellious behaviour. : r/todayilearned reddit.com
3. Early life of Joseph Stalin en.wikipedia.org
4. Stalin as a Theological Student | Political Theology Network politicaltheology.com
5. Joseph Stalin en.wikipedia.org
6. Joseph Stalin Study Guide: Seminary and Marxism | SparkNotes sparknotes.com
7. Joseph Stalin Arrives marxists.org
8. Was Joseph Stalin once a seminarian? - The Straight Dope straightdope.com