Well, are you trying to follow God with all you’ve got? Going to mass, communion, etc? If you stick close to God hopefully you will make less bad choices and less chance for the devil to have a foothold. But if you stray from God it is more “fair game” for the devil and he can reak havok on your “city without walls!”
But remember, even when we make bad decicions, and the devil intends bad,
“everything turns out for the good for those who love God, who are called according to His purpose”
I did some stupid things in my life, esp when I was strayed from the Lord, but HE in his infinate wisdom (which is above time) knew what I would do, and worked everything out for GOOD because I love Him and He loves me, get it?! God bless!!!