REV.22: 16 says these things i testify unto the churches , this is not all mankind without exception, its addressed to the churches.

quote;
If people do not have a choice in getting saved, then why did Jesus give the commission in Mark 16:15-"Go ye into ALL the world, and PREACH THE GOSPEL to EVERY creature" , why are we told that if they don't have a choice? end quote.

When a person is born again , God gives that individual in the new birth the ability to keep his commandments, and we are told in 1 Jn.3:23 This is his commandment that we should believe.
Ezek.11:19-20 tells us what God does in the new birth.
I will take the stoney heart out of your flesh and i will give them a heart of flesh that they may walk in my statutes and keep my ordinances and do them.
So God gives you the new heart so you are able to keep his commandments , one of which is to believe on the name of the Lord Jesus Christ.
God , in the new birth gives you the ability to believe . The preaching of the Word of God gives the opportunity to exercise the ability.
Most people think that the preaching is what gives us the ability to believe.
We cannot here God's words if we are not of God. If we don't have the ability to believe we will not see the truth of the gospel. Notice what Paul said in 2 COR.4:34 If the gospel is hid it is hid to them that are lost.
Notice that the gospel here is referred to as a shining light.
If an individual has no faith he doesn't see it because he's blind , He doesn't have the ability to see,
so that understanding it like that, we draw this conclusion, that faith is to the word of God as sight is to light.
Sight is the ability to see , but if there's no light no matter how good your vision is you will not see.
Every child of God who has been born again has sight , but he can't see till the light shines.
So the purpose of the gospel is to provide the light so the born again child of God with sight can see.
If God hasn't given a man the ability to believe, you can preach till your blue in the face and it will have no effect.