The reason Jude wrote

“Dear friends, although I was very eager to write to you about the salvation we share, I felt I had to write and urge you to contend for the faith that was once for all entrusted to the saints.” Jude 1:3
Jude tells us that when he sat down to write his epistle, he was originally going to write a letter of encouragement concerning our common salvation. However, the Holy Spirit impressed upon his heart to write a very different kind of letter: exhorting us as believers to “contend for the faith”. In his letter he talks about false teachers: how to recognise them, and the future judgement that awaits them. He reminds us to persevere in the faith and go about the Lord’s business.
What does it mean to “contend for the faith”? The Greek word translated ‘contend’ is epagonizomai, from epi = over/upon, and agonizomai = to agonise, struggle, as when competing for a prize or fighting against an adversary. If you had obtained something very valuable, and someone was scheming to try and take it away from you, you would defend it and safeguard it, right? Our faith – the Christian gospel and the effect it has in our lives – is the most valuable thing we have. And we have an enemy who would love for it to be ineffective. He will send all kinds of attacks our way, both overt and covert. There will be those who engage aggressively against you, and there will be those who call themselves Christians who want you to adopt some weird doctrine of theirs. We are to uphold the faith, and defend it against false teaching. We don’t need to prove the Bible, because the Bible proves itself; we are to use it to counter false doctrine when it comes. To do this we need to know what the Bible says. Are you contending for the faith today?