"I do not believe the issue is a matter of anyone "paying homage" to anyone else, or to any other "Church". The joint effort is not a "missionary" effort to "spread their version of the truth through ministry". As individuals and as contributing churches the joint effort of helping the poor is a mutual expression that comes, individually, from the persons and from each church, as an expression of something they feel called to do - helping the poor. It is not an effort that makes any attempt to say "I endorse you" or "you must endorse me". It is a mutual effort that endorses something they each feel called, in their own way, to do."
Refusing to work with other denominations is about pride (a sin), not faith. Many churches compete with one another, it seems, for tithes, rather than working together for universal salvation and charity. Within 25 square miles of my town, there are several churches. A large, well funded Baptist church, a tiny, home-based Pentescostal church, a larger Pentescostal church, a Kingdom Hall (Jehavoah's Witnesses), a Catholic church, a non-denominational church and a 7th day Adventist church.
Guess who cooperates for purposes of charity and gets the most done in the community? Roger, a lay pastor, who runs his Pentacostal church from his home (and has a huge cross on his mountain). He goes to town weekly and collects food for the needy, and distributes it to the churches with food programs, refusing to involve himself in inter-denominational warfare. The large wealthy Baptist church gets little done, and they refuse to deal with Roger and the Pentacostals. The Paster doesn't believe in working with non-Baptists. But Roger has put several travel trailors on his property and welcomes people who are down and out. If I called him today and said "my neighbor has no wood," Roger would bring him wood. The lady who runs the non-denominational church delivers food and clothing, etc..to those who don't have a car, and after a fire went through the area, she found two trailor homes for poor families who were burned out. She even obtained cat food for her pets. She found a man who gave several thousands of dollars to a formerly homeless woman (a pack rat with a dream to open a thrift shop), to rent a building for it.
Which "church" does Christ like the best? I don't think it's the one with the "correct" doctrine, rites or rituals. Or the one that emphasizes prophesy. Or the one that sends people door to door. Or the ones who believe they are the only Christians.
He would like them better if they were showing His love through their actions, rather than their doctrinal pride.
Our primary responsibility as Christians is not feeding the hungry or taking care of the poor. When Jesus fed the multitudes it was because he was SHARING THE GOSPEL with them and they were hungry while listening to him. He didn't just feed people who had no interest in the Kingdom message. That is not to say he would not help a hungry or needy individual that he came across, of course he would (the Good Samaritan), that is love. But that's not what he spent the majority of his time doing and that is not what he put the focus on.
When Jesus healed the sick or raised the dead, it was a foreshadowing of what would happen under his kingdom (Rev. 21:3,4). Yes, it came from his compassion and goodness, but his purpose while on earth was to spread the good news. And as followers of Christ, that is our primary mission as well. Matthew 24:14, Matthew 28:19,20 and many other scriptures make it clear that our primary responsibility as Christians is to share the good news of the kingdom. We will not be able to feed all the hungry, heal all the sick, raise any dead, or care for all of the poor, in fact, they'd always be with us in this system of things. As long as Satan rules the world, that's how it will be.
But Satan will NOT be ruling this world for much longer, and sharing the hope of a new system under Christ's rulership is eminently more important a mission. It's what Christ did when he was on earth, it is what he instructed his followers to do, and it is what the early Christians spent most of their time doing. Not founding charitable missions, but spreading the gospel. Giving people TRUE hope and a way to really end all suffering. That is the loving thing, that's what Christ commanded.
You mentioned Jehovah's Witnesses. These are some of the nicest, honest, most giving people you will ever come across. They'll help someone in need and that is a silent witness in and of itself, but what people are most in need of is the Kingdom message and salvation.