Yes he was addressing salvation issues, as look at his opening scripture in 3;
Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto the saints.
He is saying he needed to write to them concerning salvation because that they needed to contend for the faith, and not fall for the deceptions of the false teacher or their fate will be as such as those like those in the wilderness.