Okay, often we hear people say they are going to Heaven because they are a good person. We then say (because we are taught in church) that nobody is good but God. While this is partially true, it isn't entirely true.

The Bible says:
Too often we take this to say no one is capable of truly doing good. This is not what Matthew is telling us. Matthew is telling us that no one is truly good but God.

The word used is agathos. ἀγαθός

It speaks of a good nature, honorable, distinguished, upright, and excellent. Not one is like this except God. We all have our sinful nature to us. This does not mean we are incapable of doing good.

Before Christ came into our life, we were not capable of doing good. We were lost.

The Hebrew word used is ayd. It literally means the rags used to catch the flow of a menstruating woman. Even our best works (wen done of ourselves) are nothing more than bloody tampons in the eyes of God. Works alone are worthless. They are disgusting. They are vile. They are not good. Nothing is good unless it is of God. A non-Christian can do all the "good" things they want but they will be in vain. They can donate to as many charities, visit as many retirement homes, or do as much volunteer work as they want but the works will never be good in nature.

When we are saved, we are changed forever. We have a new calling from this point on. We are no longer called to be lost in this world. We are called to be sanctified. We are called to be holy. We are called to be set aside for God.

We are created as new creatures for the very purpose of doing good for God. We take our holy and sanctified selves and finally do good.

A Christian and a non-Christian can take the same exact works. They can both go to retirement homes. They can both give to charities. They can both volunteer their time to causes. Only one of these will truly be doing good. The other will be performing works no better than filthy rags. It is not the Christian that makes these works good. It is the fact that they are being performed for God. They are being performed with God in mind and with God's purpose in mind. This alone makes the works good.

Don't forget to study up on your Bible. Use it in all your good works. Take advantage of all the profitable uses it lists. Use it as the foundation for all the good you do for God.