1. To begin with, this isn't a terribly original "objection" to Christianity, or any other religion: it's probably been around as long as there have been believers, non-believers, and outright cynics. When you hear someone making this claim, you're not hearing any great intellectual insight; you're more likely to be hearing someone mindlessly repeating a convenient cliché that he or she picked up from someone else. But it's one of the favorite arguments against religion, because (a) it makes the skeptic feel smart and strong and capable, thus massaging his or her personal ego; and (b) because it's an easy way of insulting an entire group of people for whom you have contempt.
The most famous statement of the cliché, and perhaps the most misquoted, is Karl Marx's "Religion is the opiate of the masses." (Actually, the "opiate" metaphor was probably coined first by the Marquis de Sade, the insane sexual deviate whose very name is used to describe a certain perversion, who wrote in 1797, "Religion acts merely as an opiate.") But Marx, while totally godless and implacably opposed to religion, made a much more nuanced statement. In the introduction to a work he never completed, A Contribution to the Critique of Hegel's Philosophy of Right, Marx wrote: "Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people." His statement was more poignant than bitter, and was not intended as a "cheap shot" against religious people, who he regarded as victims, not villains. But he's been misquoted by every teenage cynic and every alcoholic college professor who ever wanted to defend his or her own unbelief. In any event, if you consider "religion is just a crutch" to be a deeply intellectual statement, your intellectual forebears are the Marquis de Sade and Karl Marx. You just haven't examined the matter closely enough to know it. That sometimes happens when you're just parroting clichés.
.2. In many, many cases, the statement is true. (You didn't expect me to say that, did you?) The sad and sorry fact is that, in this fallen world, a lot of people need a crutch, or several crutches, whether physical, psychological, or spiritual. In fact, I'd go so far as to say that, at some point in our lives, all of us need a crutch, if only during a temporary crisis. It might be another person, a friend or counsellor or spouse. It might be a bank loan. It might be something else, like a bottle or a cigarette or some "primo weed." And, very often, it might be religion: attending Jumu'ah, flipping the Rosary beads, meditating on the Amitabha Sutra, or even "getting clear" with Tom Cruise and John Travolta and all the other "intellectual" Scientologists. People from every walk of life use religion as a crutch. Why deny it? People need a crutch, or many crutches. If you don't, it's not because you're smart or strong; it's because you've never been through any difficulties. You're a hothouse flower who knows nothing of the real world.
3. Finally, and most important, a very simple distinction. Forget Islam and Roman Catholicism and Secular Humanism and Protestantism. Those are "religions." Genuine Biblical Christianity isn't a religion at all, primarily (although it fits some of the definitions). Genuine Biblical Christianity is a relationship with a living Person, a one-on-One acquaintance with Jesus Christ Himself, as revealed in the Bible and proclaimed by millions who have received Him according to John 1:12. Yes, those of us who have accepted Christ have various forms of worship and various doctrines, and God knows we have plenty of churches; in that, true Christianity may be called a religion. But, at its most basic, at its most real, Christianity is a daily relationship with God.
And it's not just a "belief in God," or even a belief that Jesus was the Son of God. I believe, quite firmly, that Barack Obama and Pope John XXIII and Floyd Mayweather Jr. and Elvis Presley are, or were, real people who really existed, or who still exist - - - but I've never met any of them. I've never even seen them with my own eyes, in person. I can't talk to them. They don't know my name or my face. I can't go to them for help when I'm in trouble, or when my heart is breaking, or when I want to share some joyous news. But I can go to Jesus Christ - - - because I've met Him, when I was born again according to John 3:3-7. That was over forty years ago, when I was not quite twenty years old. And I've known Him and talked with Him and been comforted and taught and corrected by Him every day since.
Is He, as the egomaniacal cynics would sneer, my "imaginary friend?" Nope. I'm not ashamed to say that, when I've felt the need, I've consulted professional psychiatrists, and I can empirically prove, by their attestation, that I'm not delusional. (The DSM-V might not endorse my faith, but it rules out any "delusional thinking" on my part!) Can you?
Yes, "religion" is a crutch; and, like Weight Watchers or Alcoholics Anonymous, it helps many people. But it doesn't offer permanent peace, or an assurance of a personal future, like Jesus Christ does.
Jesus Christ, not "religion," is my crutch: and my Friend and my Companion and the one living Being whose love I never have to question. He's kept me alive and sane and relatively healthy when nothing else could.
What's your crutch?