The ONLY people who call Mormons “latter day saints” are Mormons themselves. I’m aware that LDS is what you wanna go by, but people don’t respect your weird heretical cult enough to do so. Revelation 22:18 clearly states your “third testament” is heresy
Catholics are called Catholics.
Baptists are called Baptists.
Lutherans are called Lutherans.
Methodists are called Methodists.
Jehovah's Witnesses are called Jehovah's Witnesses.
Muslims are called Muslims.
Jews are called Jews.
Evangelicals are called Evangelicals.
Calvinists are called Calvinists.
Quakers are called Quakers.
Buddhists are called Buddhists.
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Members of the Church of Jesus Christ are called Saints. (See Acts 9:13, 32, 41; Rom. 1:7; 1 Cor. 1:2; Philip. 1:1; 1 Pet. 1:14–15)