Master in heaven is a name that Paul coined when he was teaching the Colossian Christians to be fair to their slaves. They were to consider how God treats His people, and the fact that He is watching our behavior. The word kyrios is usually translated “Lord,” but it can also mean “sir” or “master.” In the context of Paul’s message to slave owners it means “master.”
Master in heaven in Greek:
Kyrios en ouranō
Strong’s Concordance numbers: 2962, 3372
Bible reference: Col. 4:1
Masters, give unto your servants that which is just and equal; knowing that ye also have a Master in heaven. (Colossians 4:1 KJV)
Similar names for God are king of heaven, God of heaven, Lord of heaven, and Lord in heaven.