Recently an atheist said to me: “But faith is the opposite of reason, you don’t need faith to use reason.”

I believe this is a huge misunderstanding for people today. You see, everyone starts with faith in something and then reasons from there.

St. Augustine said: “Seek not to understand that you may believe, but believe that you may understand.”

All understanding or reasoning begins with faith. Faith is not at the end of reason, but the beginning of it. An atheist would claim that knowledge comes from our senses and ability to reason. So your faith begins when you assume the validity of your senses and your ability to reason.
My question is, “What is the basis for trusting your senses and your ability to reason?” When examining this “foundation,” it breaks down to circularity:

“I trust my senses.”
How do you know that they are reliable?
“I sensed that they were.”

This is known as “Begging the question” and is a logical fallacy because of its circularity.

The only worldview that can account for the reliability of our senses is Christian worldview based on the one God, the God of the Bible.

The scripture points this out in 2 Timothy 2:25: “In meekness instructing those that oppose themselves; if God peradventure will give them repentance to the acknowledging of the truth ”

Repentance—faith in God—comes first, then the acknowledging of the truth.