2 Thessalonians 2:15 So then, brothers and sisters, stand firm and hold fast to the teachings we passed on to you, whether by word of mouth or by letter.
How many times have you gone back to your old ways just because it is easier to do? This verse does not teach that!
What is being said here is we should always try to do what the gospel teaches us – going back to what Jesus said we should do and not go off on our own ways.
Does it matter where we hear the gospel from? No; as long as it is the gospel and not someone else’s version of the truth. Stick to God’s Word!