Its not one or the other, you preach the virtues of using both. I did that (condom and pill) with all my sexual partners before I got married and it wasn't uncommon among my peer group from what I saw.
Just like you can and should preach the value of abstinence and the consequences of sex to your teen while also teaching about safe(r) sex.
Just like you can and should preach the value of abstinence and the consequences of sex to your teen while also teaching about safe(r) sex.