Do you realize, that what you believe tells God what sort of person you are? Have you ever stopped to consider exactly what you do believe? Have you ever stopped and considered why you believe what you believe?
Paul said at 1 Thessalonians 5:21 "Prove all things" (King James Version). The Greek word for "prove" there is dokimazete (dokimazete) from dokimazw (dokimazo) and it means to prove, to test. But what you have not been told is that it also means to approve, to approve after trial, to judge worthy. God does not want you just to prove all things, He also wants you to approve of all things as well. And that is different, because now the responsibility is upon you not just to prove what you believe, but also to approve of what you believe.
For instance, if you are in a church that teaches Hell fire and eternal suffering, (watch this very carefully) in your heart, you have to approve of that.
If you belong to a church that teaches eternal death for some, (again, watch this very carefully) in your heart, you have to approve of that.
What sort of a heart could approve of Hell fire and eternal suffering? What sort of a heart could approve of eternal death for some? The doctrine of Universal Salvation teaches that all will have eternal life, including Satan and the demons. And that one day, all will have the same nature as God. What sort of a heart could not approve of Universal Salvation, eternal life for all?