Contending for the faith is something all of us will probably be called to do at some point in our walk with Christ.
Essentially, contending for the faith means contending for the truth, making this sometime difficult task emotionally easier. (At least we know the truth is worth contending for, despite the reaction we may receive.)
However, we need to make sure the truth we are contending for is the truth the Bible declares.
For this reason, we may find ourselves contending for Biblical truth with religious people, especially those who call themselves ‘Christians.’ (In fact, this is the most likely scenario of contention in the life of the Christian. It is probably a scenario most of you have already experienced at some point in your walk with Christ.)
The question is: Does the Bible fully support the truth you were contending for?
Almost certainly Peter would have contended differently for the faith prior to his experience in Acts 10 than he did after. His view of the ‘truth’ was completely changed by what he witnessed taking place in the home of Cornelius. Indeed, Jesus was going to serve the Gentiles as He had the Jews, and salvation was going to be granted by grace by faith to the Gentiles just as it had been to the Jews. Had the truth changed – or had Peter been changed by the truth the Bible actually declared rather than the truth he thought he knew through his religious upbringing?
The faith Jewish Christians stood for was not supported by the Bible, and had been established by Jewish religious practice and culture. It was ingrained, but it was wrong.
We need to make sure we avoid religious arguments. They are mostly fruitless, and can have the opposite effect of being convincing in any way. (Especially to bystanders.) But to stand for the doctrine the Bible declares IS what we are called to do. (In love, of course.)
There was much Biblical illiteracy in the day of Christ and the early-days church as there is in the Church today. The problem is not so much with those who realize they do not know the truth as it is with those who think they do.