In principle yes, but it can be very difficult to hold a job as a teacher for example, and in parts of the south, it is an invitation to be run out of town. Being promoted in the military can be difficult as well.

Also, there are many states with laws that say no atheists can hold public office. Even though they hold no weight based on current SCOTUS ruling, they do still exist. The repubs work very hard to out christian each other and make elections into exactly the kind of religious tests that would otherwise be illegal. Because the dems are mostly cowards, they fall into line, making sure that everybody knows how they go to church. Even non believers in DC have to stay closeted, or fear losing their seats.