The reason why so many people feel that the Catholic church teaches a work based salvation is because it does. It is hard for them to understand that anything added to grace for salvation makes it a works oriented salvation The Bible is very clear on this. We are saved, and justified by faith alone. Good works come into play after we are saved and not before or even during salvation.
Rom 11:6
6 But if it is by grace, it is no longer on the basis of works, otherwise grace is no longer grace.
NASU
Notice in the following passage several points are made.
Eph 2:8-10
8 For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; 9 not as a result of works, so that no one may boast. 10 For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand so that we would walk in them.
NASU
#1. We are saved by God’s grace through faith.

#2. Works are not apart of our salvation.

#3. Salvation is a gift and a gift does not have to be earned or even worked for.

#4. Good are are the result of ones salvation and not before.
We are saved by grace through faith in the finished work of Christ on the cross for our salvation. This fact give the believe assurance because God does the saving and securing of our salvation for us. John 10:27-30
27 "My sheep hear My voice, and I know them, and they follow Me; 28 and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand. 29 " My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father’s hand.
NASU
If the sheep do not hear and do not follow Christ then they are NOT HIS sheep and never have been . Those who do follow Christ are His sheep. They have (present tense) eternal life and will never perish. God both saved and secures His sheep forever. Are we stronger than God that we can undue what He has aready done for us, our salvation and security? I think not unless we are more powerful than God.