OK, so suppose it's not disrespectful or hypocritical to have your child baptised even though you are not religious and have no intention to bring said child up in the doctrine etc. (I disagree with the premise, but never mind right now.) You let MIL have your child christened, for her peace of mind and because it's important to her, but where does it stop? If MIL is a regular church goer and a believer and that's important to her, do you let her take your child to church and tell him about god as if it were a fact just because it's important to her and for her peace of mind? Is it then OK for her to tell the child that those who weren't christened will go to hell, and that going to church is the right thing to do and those who don't...?
Seriously now, if your MIL was going loopy because she thought your child would develop PCOS because you are putting her into disposable nappies, would you even consider switching to cloth? Or if it really meant so much for her peace of mind that your child start on baby rice at 3 months because she thought you were starving him and hindering his brain development? Where does it stop?
And just suppose it were really important for you to not have your child indoctrinated and to let him choose for himself if he wanted to be christened when he is old enough? Isn't it incredibly disrespectful for MIL to do something you are uncomfortable with?
Look, I'm not religious, I think a lot of the beliefs in organised religion are insane and offensive and wrong, but it doesn't stop millions of people believing in them. OP said her MIL was Catholic and worried about the baptism thing. She sounded like she cared a great deal about her MIL so me and some other people suggested that she went ahead with a baptism, perhaps without OP and her OH being involved if she was comfortable with that, to ease the mind of her MIL.
It isn't the same as the baby rice thing or the nappy thing because it doesn't effect the OP or her LO in the long run, and barely affects her in the short term. Her MIL on the other hand is going to be going crazy with the idea that should anything happen her beloved grandson isn't going to heaven. That's arguably the worst possible fear for a Catholic person.
Every single person on the thread is in agreement that taking her LO to church regularly to appease her MIL isn't right, nor is allowing her MIL to force beliefs on to her LO. No one is saying that. We were talking about the possibility, if OP wanted to (no one said she had to), of letting her MIL take her LO for an hour and get him baptised. And it would be very easy to be like 'okay MIL, stops here, baptism is the compromise now we're not bringing him up Catholic so drop it'. MIL doesn't worry about eternal damnation for the time being, and LO's fate is in his own hands when he's old enough to decide. As to your last point about it being disrespectful if OP was uncomfortable- sure it would, but OP didn't say she was so we were just talking about it as a suggestion. No one said OP had to.
As to it being offensive; it isn't. It's a fundamental Catholic belief that babies need washing of original sin. It's not like a standard Christening- which by the way billions of people do without ever bothering to practise Christianity and no one bothers about that, just like so many people get married in church. If Catholics are offended by it then they're hypcrites. And it's to appease the grandmother anyway, nothing to do with the parents, and the MIL
is Catholic.
As for atheists not making religious believers do anything that goes against their beliefs; no, you're probably right. But that's because most atheists don't have beliefs that necessitate anything similar to baptism in order to save a child's soul, so it's hardly a fair comparison.
I get what you're saying about it being a slippery slope and if MIL believes now that Micah is gonna go to purgatory then she may well believe that when he's old enough to decide for himself to reject Catholicism (if he does) he'll be condemned to hell, but with the latter belief at least she has the comfort of the fact that it was within his control and not something that he suffers innocently.