Beloved, although I made every effort to write to you about the salvation we share, I felt it necessary to write and urge you to contend earnestly for the faith entrusted once for all to the saints.
KJV
Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort [you] that ye should earnestly contend for the faith which was once delivered unto the saints.
ASV
Beloved, while I was giving all diligence to write unto you of our common salvation, I was constrained to write unto you exhorting you to contend earnestly for the faith which was once for all delivered unto the saints.