You just added "in us" to the text. It does not say: "be all the more eager to make your calling and election sure within yourself". It says,
"Therefore, my brothers, be all the more eager to make your calling and election sure. For if you do these things, you will never fall, 11 and you will receive a rich welcome into the eternal kingdom of our Lord and Savior Jesus Christ." - 2 Peter 1:10-11
This verse shows that falling and being received into the Kingdom is at stake with this election. Our calling and election hinge on doing "these things" (because they are a result of genuine faith). It is not just being sure of it "in us" so we feel better that we "elect" will never fall and will receive a rich welcome because we've been elected to it.
God has sovereignly chosen to elect those who genuinely have faith in Him.
Without the signs of genuine faith your election/welcome into the Kingdom is not sure; not just "to you" or "your perception", but in actuality.
And, yes of course, God knows those He has elected because they will have genuine faith; He has elected them upon this basis. This is why He tells us in 2 Peter to make sure our faith is genuine because it affects our election, not the other way around.
Arminians say we are chosen on the basis of faith
Calvinists say we are chosen unto faith
Scripture says we are chosen on the basis of faith