We all have some kind of a belief system. We can choose to believe something or not. What we shouldn't do, is try to impose our beliefs on others. When any organization (church, government, school, etc.) attempts to make its members, citizens, students believe certain things or act against their will, they are overstepping their bounds.

Belief should not be compulsory in any form.

So, as far as the strictly conservative evangelical movements go, they are free to believe as they wish, and they shouldn't be expected by outside forces to change with the times or the new ideals of society. If someone doesn't believe what is preached, they can certainly leave and join another church or faith that believes as they do, or see if they can get the movement/church to make changes (however that might happen).

Regarding beliefs, each one of us arrives at our convictions through experience and what we perceive to be true. Being conservative or more liberal comes about through what we're taught, and how those teachings ultimately line up with what we feel.

I'm not an evangelical, but many would consider the doctrine I follow to be quite conservative, even though, relatively speaking, others would be more strict.

There comes a point, though, where everyone needs to determine whether or not what they believe, or what they're following, is right. In the case of evangelicals, I would guess they believe it's God's will they are following. If that's true, that it is really God's will, then they would be right to follow it, rather than straying from the truth.

If it's actually man's interpretation of God's will, then there's a problem. Man's ways are not God's ways, and the former needs to align with the latter.