Sex during lent

“Christians don’t have sex during lent” one of my friends told me as preached by their priest in youth seminar.

I am a roman catholic and my friend belongs to a different sect and calls himself Christian.

I questioned him “how can a priest know whether one had sex or no?”.

And his reply “but Jesus can know”. Seriously Jesus - he never had sex in his 33 years of human existence .

Christians celebrate lent to prepare themselves for easter . 40 days of saying no to non-veg (for catholics), meat , egg and diary products (for orthodox ) .

Alcohol and smoking is also limited or abstained. But sex never heard off ;Why sex in first place?.

The priest teaching my friend gave an example of a thirummeni (bishop)  who never gave baptism to a child. He asked birth date to the child's parents and calculated and told that they had sex during the Lenten season and so baptism won’t be given.To be pure and not be tempted from Satan is a Christians moral duty was the advice from bishop.

I knew that unmarried sex is prohibited in Christians and muslims don’t have sex during Ramadan; but never knew Christian view about the same.

Christians say that people should abstain from wrong-doing during this time.

Why should church be so concerned about ones personal life?.

 Is sex a wrong doing for Christians during lenten?