Paul the apostle was a monster before his conversion to Christ, seeing Stephen stoned to death and dragging people off to prison. God changed him. He became a man who loved people and a man people loved.
The last time Paul saw elders from the church at Ephesus, he warned them that teachers of false doctrine would appear in their church (Acts 20:28 - 31). He wrote to Timothy, who was at Ephesus, warning him of false teachers in the church there and encouraging him to preach sound doctrine, resisting "profane and old wives' fables" and "useless wranglings of men of corrupt minds" (1 Tim 1:3 - 7, 18 - 20; 4:6, 7; 6:3 - 5; 2 Tim 2:14 - 18; 3:13, 14; 4:1 - 4).
It seems like the elders at Ephesus did a good job. Years later, when John the apostle had the revelation that became the book of Revelation, Jesus told him to write to the church at Ephesus, letting them know what He had to say about them: "I know your works, your labour, your patience, and that you cannot bear those who are evil. And you have tested those who say they are apostles and are not, and have found them to be liars; and you have persevered and have patience, and have laboured for my name's sake and have not become weary" (Rev 2:2, 3).
Unfortunately, something else had occurred that needed their attention: "Nevertheless, I have this against you, that you have left your first love" (v4). Yet Jesus gave them a promise: "To him who overcomes I will give to eat from the tree of life, which is in the midst of the paradise of God" (v7).
Maybe a Christian is reading this just now who has battled for years against some particular thing and has won. But something else has cropped up and you feel it is all too much and you feel like packing in. Don't do it. Jesus says "I know your works, your labour, your patience. . . "
Jesus has a promise for you. "To him who overcomes I will give to eat from the tree of life, which is in the midst of the paradise of God." Stay faithful, and one day we will fellowship with the Father, the Son, the Holy Spirit, the angels and all the saints in the New Jerusalem, where righteousness rules and there is no sickness, no pain and no sorrow.
Keep on battling on. It will be worth it all.