Evangelist Prestige class and save progression

The Evangelist Prestige class level 2 feature, Aligned Class (Ex) states as follows:

Evangelists come from many different backgrounds, and they show an unusual range of diversity. At 2nd level, the evangelist must choose a class she belonged to before adding the prestige class to be her aligned class. She gains all the class features for this class, essentially adding every evangelist level beyond 1st to her aligned class to determine what class features she gains. She still retains the Hit Dice, base attack bonus, saving throw bonuses, and skill ranks of the prestige class, but gains all other class features of her aligned class as well as those of the evangelist prestige class. (emphasis mine)

I cannot understand one part. Suppose I am a 5th level Bloodrager, and from 6th level onwards I take levels in the Evangelist Prestige class.

Once I get to level 15 (bloodrager 5/evangelist 10) I’d go back to being a Bloodrager for the last 5 character levels.

My problem is, for the first 15 levels I add the save progression of bloodrager (class and character levels 1 through 5) to the one of Evangelist (class levels 1 to 10, character levels 6 to 15). When I level up to 16th level, which level of the bloodrager saves do I add? Do I start counting up from Bloodrager 14 (on account of Aligned Class) or from bloodrager 6 (since I’m not actually gaining bloodrager levels, just the relevant class features)?