It's biblical to "pray for people" you know are weaker in the faith or who are even outright sinning. But don't forget that Scripture also commands us to confront those people - TALK to them so they can know what they're doing wrong and why they need to make a correction in their thinking or behavior.
Way too many tend to take Scripture passages out of context via their "Greek" mindsets, and are under the erroneous assumption that we shouldn't "judge others." Well, correcting a brother or sister according to TORAH is NOT "judging!" Torah says to DO something so that their blood won't be on YOUR hands! (Some pertinent scriptures below.)
I can't tell you how often I've been warned to "just pray" and "leave it up to God, because only He can change someone's heart."
While it's true, His Word ALSO tells us to get off our duffs and DO something! I mean, if someone is getting ready to walk off a cliff, are you going to yell "STOP!" or are you going to get down on your knees to ask God to keep them safe?
If your toddler is getting ready to walk out into the traffic, are you going to yell loudly and jerk him back from the road - or are you going to sit back and pray for him?
The truth is, you can pray AFTERWARD, after you've done something to help that person back onto the path.
Ezekiel 3:17 “Son of man, I have made you a watchman for the house of Israel. Whenever you hear a word from My mouth, give them a warning from Me. 18 If I say to the wicked man, ‘You will surely die,’ but you do not warn him or speak out to warn him from his wicked way to save his life, that wicked man will die in his iniquity, and I will hold you responsible for his blood. 19 But if you warn a wicked man and he does not turn from his wickedness and his wicked way, he will die in his iniquity, but you will have saved yourself.…
Galatians 6:1 Brothers, if anyone is caught in any transgression, you who are spiritual should restore him in a spirit of gentleness. Keep watch on yourself, lest you too be tempted.
1 Timothy 5:20 As for those who persist in sin, rebuke them in the presence of all, so that the rest may stand in fear.
Titus 1: 13. And this testimony is true. Therefore rebuke them sharply that they may be sound in the faith 14. and may not throw themselves into Jewish fables and into the precepts of men who hate the Truth. 15. For to the pure, everything is pure; but to them who are defiled and unbelieving, nothing is pure; but their understanding is defiled, and their conscience. 16 And they profess that they know Elohim, but in their works they deny him; and they are odious and disobedient and to every good work reprobates.