How can you tell if a Christian does good for the right reason?

look for obvious signs...but still, you may never know

An act driven by fear derives a deed of selfishness. Heaven or Hell is not reaped by fear, but choice of doing what is right despite of fear - courage. No one can be certain of the reward of Heaven, by everyone can be confident in the Hope of Heaven by the courage to be righteous.

The Christian does good for the same reason a non-Christian does...they believe it to be good.

If an old lady falls down my motivation to help her up is not derived from contemplating the eternal blessings if I do and damnation if I don't. The properly informed and functioning conscience is guided by natural law to recognize and be drawn to choose good over evil moral acts.

A true Christian has accepted the gift of eternal salvation from Jesus Christ. That's all there is to it. They've 'accepted' a free gift, not because of their hard work, or deserved reward, but of recognition that they are natural sinners and want God to be with them.

As such, Christians are to emulate Christ through their actions, not out of fear, but out of a desire to glorify God. I've personally accepted Christ. If I don't help you cross the street, I'm not going to Hell. If I get impatient and angry for a reason I ought not to, I'm not going to Hell. A Christian does not deal with Heaven or Hell once they are saved. They are to please God in all things with their best efforts.

The Bible clearly indicates 2 different areas of judgement. A believer in Christ will be evaluated and rewarded accordingly. An unbeliever will be evaluated condemned accordingly. The Bible also instructs that it's a heart issue. If I give my money to the church because I think God will make me rich, it's not Biblical and God won't bless me for it. If I give with a soft heart wanting God to use my money to spread the gospel, God will bless me in Heaven for it, and may or may not bless me on Earth. Reasons for doing things are always very important.

The best way you can tell if they are doing it genuinely is if they are a REAL Christian. Validate the fruits of the Spirit in them and see if their walk matches their talk.

I defy you to prove that that is selfish. Is a man selfish if he does good to his future wife. Rather you have it backwards as all selfish (that's right !!! You must be) idiots imagine.

Apparently GOD most certainly can.

Look at the results.