You don't need to know everything to refute someone's unbiblical idea. Just read the context.
Several years ago I was invited to a maximum-security state prison on the border of the United States and Mexico. The chaplain wanted me to equip the Christians that were in prison there to witness to their Muslim friends. A lot of these Christians are in a cell for a very long time with Muslims.
Word spread that I’d be talking on Islam not only to Christians, but to the Muslims as well. That afternoon when I began my teaching, I had both Christians and Muslims in the audience.
At the end of my teaching, a Muslim raised his hand. He said, “Did you know that Jesus in the Bible prophesies the coming of Mohammad?” I asked him where I could find the passage in question. He responded, “In John 14:16 Jesus says, ‘I will send another helper who will guide you in all truth.’"
In some English translations the word helper is changed to advocate. The point is, the Muslim said this: “The Greek word for helper is parakletos. In the Qur’an, Muhammad is referred to as a paraklitos. So you can see the similarities there. Perhaps the Bible just got some of the text wrong in the Greek. Perhaps what Bible meant to say ‘he will send another helper (paraklitos).’ Jesus is predicting the coming of Mohammad.”
That was a problem for me because here I was standing in front of a huge audience, and I didn’t know Greek. How was I going to answer this person? Here’s what I did. I opened up my Bible and turned to the passage. I quickly scanned the context – the words before and after the verse. I found that just 10 verses afterwards, in verse 14:26, Jesus Identifies the helper, comforter, and advocate.
It says, “I will send a helper, the Holy Spirit, who will guide you in all truth.” In other words, Jesus, by identifying who this helper is, rules out the possibility of Mohammad. Notice, I didn’t actually have to know Greek grammar or vocabulary. Simply looking at the context, I was able to respond to this Muslim (who conceded that my argument made sense).
Reading the context is so important, and many times it can be even more important than knowing the Greek and Hebrew than a scholar might think. Don’t shortchange the importance of good hermeneutics. Context, history, genre, these are the three keys. This was just one example of how context can be so powerful in helping you address common challenges.