Our thoughts and actions condemn us:
Romans 1:18-21 NASB
18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men who suppress the truth in unrighteousness, 19 because that which is known about God is evident within them; for God made it evident to them. 20 For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse. 21 For even though they knew God, they did not honor Him as God or give thanks, but they became futile in their speculations, and their foolish heart was darkened.
We condemn ourself:
Romans 2:1-2 NASB
1 Therefore you have no excuse, everyone of you who passes judgment, for in that which you judge another, you condemn yourself; for you who judge practice the same things. 2 And we know that the judgment of God [fn]rightly falls upon those who practice such things.
The LAW will condemn us:
Romans 2:12-16 NASB
12 For all who have sinned without the Law will also perish without the Law, and all who have sinned under the Law will be judged by the Law; 13 for it is not the hearers of the Law who are just before God, but the doers of the Law will be justified. 14 For when Gentiles who do not have the Law do [fn]instinctively the things of the Law, these, not having the Law, are a law to themselves, 15 in that they show the work of the Law written in their hearts, their conscience bearing witness and their thoughts alternately accusing or else defending them, 16 on the day when, according to my gospel, God will judge the secrets of men through Christ Jesus.