When people who claim to believe in God consistently disobey Him, hurting us and those we love, this can be extremely frustrating, even debilitating, too painful to bear. (Ps 73:16) As we ourselves try our best to follow God, we naturally expect others in the Faith to do the same. But it isn’t so, at least it doesn’t appear to be.
Perhaps my biggest mistake in life so far, which I think I’ve been making most of my life, is expecting Christians to do the right thing as a manner of life, getting frustrated, bewildered and upset when they won’t, and trying to change them. For years, the appearance of habitual, willful sin in others who claimed to be believers has destabilized me, tempting me to bitterness and resentment.
If you find yourself struggling here, let me ask, would your pain diminish greatly if you knew the people hurting you and those you love are either  unbelievers, haters of God and His elect, living lives of willful sin, or  trying their best to obey God in their circumstances, such that if you could see what they do you’d be content that they’re doing pretty well, all things considered?
Regardless of appearances, this is, in fact reality: every child of God consistently tries their best to follow YHWH — and no one else does. (1Jn 3:10) Understanding this changes everything, at least for me. (Ps 73:17)
Yet even knowing this, it seems to take repeated experience over time to work it down into my soul as experiential reality (Ro 5:3): YHWH’s restraint is the only reason anyone’s remotely good (2Th 2:7), and He has a reason, a perfectly coordinated plan, in absolutely everything He allows. (Ep 1:11)
Yes, God is good and His plan is amazing; we saints are going to rejoice in it one Day, but as He’s working it out we’re often in pain (1Pe 1:6), and it can be overwhelming. (Ro 8:23) He routinely allows very difficult situations in our lives, and exhorts us to count it all joy. (Ja 1:2)
I think the reason we should rejoice in trouble like this is because a primary objective of God’s plan is to glorify Himself by transforming His elect into His likeness (Ja 1:3), such that we rejoice in Him, living lives of purity and joy in the midst of a crooked and perverse nation (Php 2:15), esteeming others better than ourselves. God wants us to struggle through these difficulties with Him, with this singular objective in mind, as He works out his will in and through us. His plan works to achieve His end, conforming us more and more into His image, and it’s evidently the best way to do so.
Unbelievers are just unwitting pawns in this design (Ep 2:2); the enemy positions them in our lives as apparent Christians (2Co 11:14) such that we can’t generally tell one from another. (Mt 13:28-29) The lost often don’t have any clue why they appear to be outwardly good, or why life seems to work for them without God, but they’re content that it does, and this destroys them. (Pr 1:32)
The more fully I accept and internalize this perspective, accepting the reality of sin, even in those who claim faith in Christ, without becoming frustrated and alarmed, the less painful life will be. What remains is to cleave to JEHOVAH, walk worthy of Him, grow in love, sorrowing for the lost as they miss out on YHWH and His transforming work, acknowledging that I’d very likely be doing worse were I in their shoes, and praying for YHWH to be merciful to them.