None of us have all the details. -- How are we going to give meaningful advise or answers to this question?
- Did you KNOW that your son-in-law was an atheist and anti-religion? - it would be hard for you to NOT know this about him. Sounds like he's pretty emotional about it.
- Have you discussed this with your daughter? Has she shared her faith with her son? Sounds like if he is 7 and hasn't heard about God - then it is likely that your daughter is raising him atheist as well.
- Did you consider their thoughts or feelings when you talked to your grandson about God OR were you selfishly trying to teach him about your faith, knowing they don't share those beliefs? OR was it done without thinking, and perhaps rashly?
- Does easing someone's emotional pain always justify one's actions? Perhaps emotional pain is part of life and helping him to get through it a BETTER lesson, then using it as a way to teach him about God.
- Why haven't you taught him about God BEFORE he's 7? Why wait 'til now? - Same question to your daughter.
- Perhaps this issue should have been worked out prior to this. Perhaps his lack of religious upbringing should have been a topic of discussion when he was 4 or 5 or 6yrs. old.
Questions into the intricacies of a family conflict could go on and on... but as it usual, the issue most likely started a while ago and hasn't been correctly addressed, which is WHY it sorta blew up.
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You ARE part of the family.. so you have a limited stake in HOW the child is being raised. - which includes his religious upbringing.
BUT, your role is secondary to that of the parents. Faith and religious education starts at HOME with the parents. Aunts, Uncles, Grandparents, Cousins all have secondary roles in raising a child.
So you need to recognize your place. RIGHT?
I think that you SHOULD admit that you perhaps acted rashly and moved too quickly to soothe your grandsons feelings without giving thought to the larger issue (his parent's intentions and obvious lack of religious upbringing.)
I think you SHOULD apologize for acting without thinking and without consulting with them, first. For NOT respecting their PRIMARY role as educators and leaders within their family.
This doesn't mean that you harmed him or 'taught him a fairytale' - what you said may be absolutely correct - but the WAY you went about it may have been wrong.
I think you are also DUE some apologies from your son-in-law for how HE acted and the things he said in the 'heat of the moment' If he insulted your wife (his mother-in-law) then he should apologize to her, as well.
I think you COULD use this as a larger discussion with your daughter and son-in-law regarding their beliefs and how they intend to raise your grandson and to spell out your role in his upbringing. This could be actually a mistake turned into a wonderful opportunity to clarify and get on the same page. Every conflict has a positive side, if you take advantage of it.
This is also an opportunity for you to re-evaluate YOUR role and how YOU are relating to your grandson.
Are you over-reactive in trying to 'fix' his every bump n bruise, his every negative feeling?
Are you 'helicoptering in' as they say - always to the rescue, always being the hero and robbing your son-in-law and daughter their proper role in being the actual parent?
Could SOME of their hurt feelings be about HOW you always try and fix things, in general?