John the Baptist and Jesus Christ opened their ministries on Earth calling for repentance (Matthew 4:17, Mark 1:15). Jesus, in His Revelation to John, called the church of Ephesus to repent.
Revelations 2:5 Remember therefore from where you are fallen, and repent, and do the first works; or else I will come to you quickly, and will remove your candlestick out of its place, except you repent. (KJVER)
The Revelation might be shrouded in symbolism but Jesus was clear in His admonition. They need to μετανοέω (metanoeo) the Greek word translated ‘repent’ in the New Testament. Do ‘the first works’? Believe, for those who have not yet believed, and for many, get back to God!