They disagreed over Religion.

My hope is that I go to Turkey in the summer of 2015 or 2016.

My attempt:

Din için anlaşmadılar.

Umudum 2015 veya 2016 yazında Türkiye´ye gideceğim.

My try as learner:

They disagreed over Religion.

Din konusunda anlaşmadılar. (or maybe: Din konusunda aynı fikirde değildiler ?)

My hope is that I go to Turkey in the summer of 2015 or 2016.

Umarım Türkiye´ye 2014 yoksa 2015 yazında gidebilirim.

Unfortunately, not 100% sure about it - better wait for corrections from other forum members.

"Din konusunda aynı fikirde değildiler."    is good.

"Din konusunda anlaşmadılar."   is not. It means "they didn´t agree ...", not "they disagree ..."

Different.

"Umudum" sounds strange. In English it is kind of the same. You don´t say "my hope is ..." you say "I hope ..." In Turkish it sounds much stranger.

"ya da" is much better instead of "yoksa"

Putting "yoksa" makes it sound like 2015 is the worst case scenario. But even if that´s what you mean, you don´t use "yoksa." You use "ya da en kötü" or "ya da en olmadı" or "ya da en geç"

"Umarım Türkiye´ye 2014 ya da en olmadı 2015 yazında gidebilirim."

Olphon, many thanks for your altruism Btw, at first I thought about putting there "ya da", but somehow decided to use "yoksa"...

"Ölüyü çok yıkarsan ya osurur ya sıçar." - Turkish proverb

I guess the hidden meaning is that if you work too carefully on something then you will always do something wrong?

Exactly