In actual fact, to even have this question you must believe that you have free will, otherwise, what would it matter if you were in or out of God's will, you were predestined!
So what measure or measures do you you use to determine if you are in God's will?
Firstly, there are the obvious things like the 10 commandments
- Have no other gods
- Have no idols
- Do not use the Lords name in vain
- Remember the sabbath
- Honour you father and your mother
- Do not murder
- Do not commit adultery
- Do not steal
- Do not give false testimony
- Do not covet
Now most honest people will realise that they do not keep all 10 all the time, however it gets even more drastic when you take into account what Jesus said in the sermon on the mount that even committing these acts in your heart is sin.
1 John 1:8 says: If we claim to be without sin, we deceive ourselves and truth is not in us. So at the first level we are always out of God's will, not just because we sin but because we aren't perfect... to be continued!