This is what we are called to do:
2 Timothy 4: 1 I charge thee therefore before God, and the Lord Jesus Christ, who shall judge the quick and the dead at his appearing and his kingdom; 2 Preach the word; be instant in season, out of season; reprove, rebuke, exhort with all longsuffering and doctrine. 3 For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears; 4 And they shall turn away their ears from the truth, and shall be turned unto fables. 5 But watch thou in all things, endure afflictions, do the work of an evangelist, make full proof of thy ministry.
We are told to reprove, rebuke and exhort.
Reprove is elegcho in the Greek which means to –convict, convince, and tell a fault. Is this not what people call judging these days? Why yes it is. So if we are instructed within the Bible to tell those that sin of the faults and we are to convince them to turn from the error of their ways. Then are we judging them? No we are not, we are a tool of God, one of His servants through the grace of Jesus Christ, as long as we do not do the same sin and use facts found within the Bible.
If we do not reprove those that sin, if we do not rebuke those that sin and if we do not exhort them to turn from their sins then are we not in disobedience to God? Yes we are.
So yes love the person that sins, and yes hate their sin for their sin is more important to them then God and for this reason alone you must tell them of their sin. You must ask them time and again to turn away from that which is evil, which is of this temporal existence. For our ultimate goal is not to be happy here, but to be eternally joyous in our service to God in our eternal life promised to us by the Bible.
We are to learn how to do that service here in the short time here upon this plain of existence. Then we are to learn more during the thousand year reign of Jesus Christ Himself who we as His body are to serve alongside Him and learn from Him. Teaching, caring, instructing those that either survive the Great Tribulation or come after it.
Even in this time there will be failure for at the end of the thousand year Satan is to be let loose upon those that live upon the earth at that time and others will choose to follow him into the abyss than to serve God and His Son the Lord Jesus Christ, which is the fate for all that chose the sin over God.