The short answer is yes, but I will explain why and what I highly recommend.

First of all both programs, though they are security type applications, do different things. Firewalls will detect and stop hackers from breaking into your computer.  This is a must, particularly if you have a cable modem connection.  When you're connected at all times, people can easily hack into your computer and cause many things to happen, such as steal personal data from you or perhaps delete data that is crucial to you.

An antivirus program will detect and remove most computer viruses provided that you have the data file up to date. There are some antivirus programs that detect viruses only in email.  Though this is where most viruses do enter your computer, you should have one to detect a virus from any other source, such as a floppy disk or CD.  A friend could have given you the CD, not knowing it had a virus.

And, when you have both a firewall and AV program,  the best thing to do is buy a security suite, though I won’t name any as I won’t endorse one vendor over another.  Sometimes when you buy standalones, there are conflicts between them and you are no further ahead.  You may actually be further behind the eight ball as neither functions well.  Most antivirus vendors do make suites.