The teen died after a crash took place in the Barony Road area of Mountfield near Omagh around 11.15pm on Sunday July 31.
Dylan was the driver of a Kia car which collided with a Mini.
Addressing mourners in St Mary’s Church, Killyclogher, Co Tyrone, Father Declan McGeehan, questioned why Dylan needed to die “at such a young age”.
“In truth we will never fully comprehend his premature death,” the cleric added.
“Family might even feel aa sense of betrayal by God. We are told from a young age that he loves us and would always help us but today we ask where was God on Sunday night?
“But God already knows how we feel and we must never fear crying out to him.”
The teenager was a pupil at Drumragh Integrated College in Omagh, Co Tyrone.
Two other people were taken to hospital as a result of the crash with serious injuries.
A death notice for the Omagh man in funeraltimes.com describes him as the ‘precious son of Janeen, dear brother of Rory, cherished grandson of Isobel, nephew of Jakki, Barry, Bryan and boyfriend of Ruby Burnside’.
Father McGeehan said after spending time with Dylan’s family it was evident that Dylan was thought to have had “a natural wit that had you laughing “.
“He was a charming young man who made a lasting impression on everyone he met,” added the cleric. “It is lovely to see so many of his classmates here today.”
Rev McGeehan added that during talks about Dylan it emerged that the teen had talked about his “dreams to become a pilot or even a submariner”.
A statement issued by Drumragh Integrated College Principal, Mrs Imelda Kirk, said "All associated with Drumragh Integrated College, Omagh, are devastated to learn of the tragic death of our student, Dylan McGahan.
"Dylan was a valued member of the College Sixth Form and had just completed his Post-16 Studies.
"Dylan will be fondly remembered for his gentle and reserved nature.
"The Board of Governors, Principal and Staff of Drumragh Integrated College extend their deepest sympathy to Dylan’s family and friends on this tragic loss."
St Ronan's Recarson Primary School
In another post, St. Ronan’s Recarson Primary School Community said they are "shocked and saddened at the untimely death of Dylan McGahan, RIP".
"A former pupil of Recarson Primary School, Dylan was grandson of our esteemed Building Supervisor, Isobel McGahan," adds the post.
"We are heartbroken for Isobel, her daughter Janeen and entire family circle.
"Please remember them all in your thoughts and prayers at this devastating time.
May he rest in Peace.
St. Ronan pray for us"
Also on social media, SDLP West Tyrone MLA Daniel McCrossan expressed his sympathy to both Dylan McGahan and pensioner Kevin McCrory who passed away on Sunday following a road traffic accident in Sion Mills last week.
Mr McCrossan said: “The local community in Omagh have been left shocked and devastated by these deaths on our roads in the last few days. Kevin McCrory was very well-known in the local area and the tributes that have been paid to him are testament to the great character that he was. The passing of Dylan McGahan at such a young age is also absolutely tragic, he was a young man with his entire life ahead of him.
“My thoughts and prayers are with both the McCrory and McGahan families and everyone who knew them at this incredibly difficult time. They have my deepest sympathies and I’m sure the local community in Omagh will rally around them as they come to terms with their loss.
“I would also like to send my best wishes to the two people injured in the crash on the Barony Road. It has been reported that they suffered serious injuries and were taken to hospital. I hope they make a full recovery as soon as possible."
He added: "One death on our roads is too many and the impact of these deaths will be felt locally for some time. I would like to thank all the emergency services for attending the scenes of these incidents and especially the air ambulance who are doing amazing work in difficult circumstances. I would urge anyone who witnessed these collisions or has any information or dashcam footage to come forward to police.”