3:11 `I am coming quickly; hold fast what you have, in order that no one take your crown.
I am COMING QUICKLY;
This is not a threat of judgment but rather a promise of Christ's second coming. This phrase is used three times in Revelation 22. Find them.
The two previous churches, Thyatira and Sardis, also were given notice of His coming. At Thyatira (Revelation 2:25), they were to hold fast until I COME otherwise a GREAT TRIBULATION waited for them. In Revelation 3:3, He would COME to Sardis as a thief and thus catch them unawares. So, the Philadelphia church, is different. They are watching and waiting so as to be kept from the HOUR of testing.
HOLD FAST WHAT YOU HAVE in order that no one take your crown.
The crown of Life had been promised to those who were faithful unto death at the Smyrna church (Revelation 2:10). Other crowns are available to the faithful. Here, the Philadelphians are to hold on to their beliefs and faith in God, lest they lose their crown.
There is the possibility to lose your rewards as taught in 1 Corinthians 3:14-15. Or, if we become weary and quit working for the Lord, we will not reap certain benefits Galatians 6:9 (whether this means not getting a crown is debatable).
However, salvation is NEVER lost if one truly makes a commitment to Christ. John 10:27-30 says Christ gives eternal Life to his sheep who follow Him! THEY SHALL NEVER PERISH!!!