How do we Know God's will?

The simple answer is that He has to tell us.
Of course, some things are obvious, and the majority of decisions and events in our lives can easily be measured against the standard of the Bible: things that disagree witht he Bible are not God's will, and vice versa.

But I think you are more interested in the things that are not so clear. In these cases, one can try to sort it out by thinking it out, and perhaps get some extra help from a trusted priest or servant or other confidant.


Is it something we always have to pray for? And will God tell you?

Absolutely. In fact, Jesus asked to do so every day in the Lord's Prayer. But you'll notice that the words do not ask God to TELL us what His will is, but only that his be DONE. Sometimes, you can end up doing God's will without even knowing it. Perhaps this helps keep us humble?

I think it's a really good policy to follow. When you pray, tell God tht you understand that He doesn't have to brief you on His plans for the universe, but ask Him to guide your actions and decisions so that whatever you end up doing, it is His will and not your own.