Believe it or not, your first thought about something is a telling indicator of your core nature.  It's your knee-jerk reaction that shows what you are made of and who you belong to— the god of this world or the One you claim as your Lord.
Ask yourself this:  When you're faced with a problem or an inconvenience, what’s your first thought?
Is it, how does this problem affect me?Or, is it how does this problem affect my family, or others, or the ones I love?
Is your first thought about you?  Or is it about the welfare of others?
Your answer may be a key indicator as to your true nature.  And your true nature is the single, most important indicator as to whether or not you're saved.  Confused?  Maybe a bit angry?  Good.  Then keep listening to find out what you need to do.
The following is a study on Colossians 2:11-15.