There seems to be some confusion here.

People are unconditionally chosen (elected) by God to belong to His Church, the body of His incarnate Son. They are not chosen on the basis of anything foreseen or anything else.

Not all people predestined to belong to the Church or even respond to the Gospel message are predestined to remain in the Church. Some are given perseverance by a true faith, some are not given perseverance having only received a temporary faith of some sort.

So, if the Church is God’s chosen people, then those who leave her no longer have the status of “chosen,” in that sense. But the fact remains that God’s decree for them to be in covenant for a time was not conditional.

What people mean when they speak of “conditional election” is that God has revealed who are the people who belong to him. When you read about the fact that God has chosen a people marked out in certain ways, you can adopt these marks and thus know you are among those people. You meet the conditions and are now known as one of the elect.

But that doesn’t change the fact that the only reason you would do this is because God chose you beforehand and drew you either effectually or by an operation of the Spirit in common with the elect but not effectually (i.e. effectual unto final salvation). Election remains unconditional.