Christograms
His abbreviations/monograms that refer to Christ. An abbreviation is a Christogram if it contains the name Christ.
They were not abbreviations because people were lazy. They functioned as Holy Signs, concentrated theology, protection, and permanent presence of Christ. Here are 4 well-known Christograms:
A Knight Templar wore them. – a monk wrote them and the Church carved them in stone. Not to read, but to be.
INRI
Iesvs = Jesus
Nazarenvs = of Nazareth
Rex = king
Ivdæorvm = of the Jews
These are the words that Pontius Pilate wrote above Jesus on the cross.
IHS Iēsous ΙΗΣΟΥΣ
The first 3 letters of Jesus in Greek.
Iota, Eta, Sigma
It is often used in Western art to symbolize Christ, and sometimes it appears on the Eucharistic host.
Only later was IHS read as “Iesus Hominum Salvator” Jesus, savior of mankind. But that is Latin and not Greek.
IC XC
- ΙΗΣΟΥΣ → abbreviated to IC
- ΧΡΙΣΤΟΣ → abbreviated to XC
A Greek abbreviation meaning Jesus Christ; along with a specific hand gesture. That gesture forms the letters.
👉 Christ doesn’t just say who He is, He shows it
The coin at the very top is Medieval Greek, or Byzantine Greek. Dating 1028.
JMJ
If you’re familiar with the Reverend Fulton Sheen, you’ve probably seen him write JMJ on the blackboard. That stands for Jesus, Mary and Joseph. It has become a common custom among Catholics to write this at the top of letters, documents, papers or blackboards.
AMGD
Ad Majorem Dei Gloriam
To the greater glory of God. This abbreviation comes from Saint Ignatius of Layola, Spain. 
As an extra: the abbreviations IHSV and NNDNN are not Christograms: the name Christ is not in them.
IHSV In Hoc Signo Vinces in this sign you will overcome
NNDNN Non Nobis, Domine, Non Nobis Sed Nomine Tuo Da Gloriam
Not to us, O Lord, not to us, but to your name give glory
